# Big Ideas Math Answers Grade 2 Chapter 2 Fluency and Strategies within 20

## Big Ideas Math Book 2nd Grade Answer Key Chapter 2 Fluency and Strategies within 20

Understand all the concepts of BIM 2nd Grade Solutions for 2nd Chapter Fluency and Strategies within 20. Most of the students may think that learning fluency and strategies within 20 is not an easy topic. So, we are giving a detailed step by step explanation for all the topics in a simple manner. So go through the following sections and start your preparation with love and joy.

The different topics in Big Ideas Math Grade 2 Chapter 2 Fluency and Strategies within 20 Solution Key are Add in Any Order, Use Doubles, Add Three Numbers, Count On and Count Back to Subtract, Relate Addition, Subtraction, and others.  Just tap the below links and start your preparation. By using these links you can score the highest marks in the exams.

Vocabulary

Lesson: 1 Add in Any Order

Lesson: 2 Use Doubles

Lesson: 4 Make a 10 to Add

Lesson: 5 Count On and Count Back to Subtract

Lesson: 6 Relate Addition and Subtraction

Lesson: 7 Get to 10 to Subtract

Lesson: 8 Practice Addition and Subtraction

Lesson: 9 Problem Solving: Addition and Subtraction

Chapter: 2 – Fluency and Strategies within 20

### Fluency and Strategies within 20 Vocabulary

Organize It
Use the review words to complete the graphic organizer.

Define It
Use your vocabulary cards to match.

Question 1.

### Lesson 2.1 Add in Any Order

Explore and Grow

Use the table to ﬁnd the sum. Change the order of the addends. Write the new equation.

Explanation:
Changing the order of the addends does not change the sum.
The expressions 5 + 6 and 6 + 5 are both equal to 11. The expressions is represented by red color and sum by green.
The expressions 4 + 9 and 9 + 4 are both equal to 13. The expressions are represented by blue color and sum by yellow.

Show and Grow

Question 1.

Explanation:
Changing the order of the addends does not change the sum.
The expressions 6 + 3 and 3 + 6 are both equal to 9. The addend 6 is represented by orange color and addend 3 by blue.

Question 2.

Explanation:
Changing the order of the addends does not change the sum.
The expressions 5 + 1 and 1 + 5 are both equal to 6. The addend 5 is represented by yellow color and addend 1 by green.

Find the sum. Then change the order of the addends. Write the new equation.

Question 3.

Explanation:
Changing the order of the addends does not change the sum.
The expressions 8 +2 and 2 + 8
are both equal to the sum 10.

Question 4.

Explanation:
Changing the order of the addends does not change the sum.
The expressions 4 + 3 and 3 + 4
are both equal to the sum 7.

Apply and Grow: Practice

Find the sum. Then change the order of the addends. Write the new equation.

Question 5.

Explanation:
Changing the order of the addends does not change the sum.
The expressions 4 + 3 and 3 + 4
are both equal to the sum 7.

Question 6.

7 + 3 = 10                   3 + 7 = 10
Explanation:
Changing the order of the addends does not change the sum.
The expressions 7 + 3 and 3 +  7
are both equal to the sum 10.

Question 7.

6 + 5 = 11                     5 + 6 = 11
Explanation:
Changing the order of the addends does not change the sum.
The expressions 6 + 5 and 5 + 6
are both equal to the sum 11.

Question 8.

17 = 9 + 8                         17 = 8 + 9
Explanation:
Changing the order of the addends does not change the sum.
The expressions 9 + 8 and 8 +9
are both equal to the sum 17.

Question 9.

2 = 0 + 2                          2 = 2 +0
Explanation:
Changing the order of the addends does not change the sum.
The expressions 0 + 2 and 2 + 0
are both equal to the sum 2. Adding 0 to any number gives the sum the number itself.

Question 10.
DIG DEEPER!
Which shape completes the equation?

Explanation:
Changing the order of the addends does not change the sum.

Think and Grow: Modeling Real Life

You paint 12 shapes. 8 are rectangles. The rest are circles. How many circles do you paint?
Write two equations that describe your shapes:

Given:
Total number of shapes painted = 12
Number of rectangles painted = 8
Number of circles painted = total shapes painted – number of rectangles painted
12 – 8 = 4
8 + 4 = 12
4 + 8 = 12
Total circles painted = 4.

Show and Grow

Question 11.
There are 13 race cars. 6 of them have numbers. The rest do not. How many race cars do not have numbers?
Write two equations that describe your shapes:

_______________________________
_______________________________
_______________________________
Total number of race cars = 13
Number of race cars with numbers = 6.
Number of race cars without number = total number of race cars – Number of race cars with numbers
13 – 6 = 7.
number of race cars with number + number of race cars without number = total number of race cars
6 + 7 = 13
when we reverse the order
7 + 6 = 13
Explanation:
Changing the order of the addends does not change the sum.
Given total race cars = 13
Race cars with number = 6
To find the race cars without number we need to minus race cars with number from the total
13 – 6 = 7

### Add in Any Order Homework & Practice 2.1

Question 1.

Explanation:
Changing the order of the addends does not change the sum.
Adding blue and red gives the sum.
6 + 4 = 10.
when we reverse the colors order
adding  red  and  blue gives the sum .
4 + 6 = 10.

Question 2.

Explanation:
Changing the order of the addends does not change the sum.
Adding yellow and orange cube gives the sum
1 + 8 = 9.
when we reverse the colors order
adding orange and yellow cubes gives the sum
8 + 1 = 9.

Find the sum. Then change the order of the addends.
Write the new equation.

Question 3.

7 + 0 = 7                      0 + 7 = 7
Explanation:
Changing the order of the addends does not change the sum.
Adding any number to 0 gives the sum the number itself.

Question 4.

2 + 4 = 6               4 + 2 = 6
Explanation:
Changing the order of the addends does not change the sum.
The expressions 2 + 4 and  4 + 2 gives the same sum 6.

Question 5.

15 = 8 + 7                       7 + 8 = 15
Explanation:
Changing the order of the addends does not change the sum.
The expressions 8 + 7 and 7 +8  gives the same sum 15.

Question 6.

11 = 3 + 8        8 +3 = 11
Explanation:
Changing the order of the addends does not change the sum.
The expressions 3 + 8 and 8 + 3 gives the same sum 11.

Question 7.
Number Sense
Complete each equation.

Explanation:
Changing the order of the addends in the expressions.

Question 8.
Modeling Real Life
You have 14 blocks. 8 are cubes. The rest are cylinders. How many cylinders do you have?
Write two equations that describe your blocks:

Total number of Blocks = 14
Number of cubes = 8.
Number of Cylinders = total number Blocks – Number of Cubes
14 – 8 = 6.
Number of cylinders = 6
number of Cubes + number of Cylinders = total number Blocks
8 + 6 = 14
when we reverse the order the expression
6 + 8 = 14
Explanation:
Given total Blocks = 14
Number of cubes = 8
From the above calculation
Number of Cylinder = 6
Blocks = number of cubes + number of cylinders
8 + 6 = 14
Changing the order of the addends does not change the sum.
6 + 8 = 14.

Question 9.
Modeling Real Life
There are 16 kids in a class. 7 have gone camping. The rest have not. How many kids have not gone camping?
Write two equations that describe the kids:

Total number Kids in the class= 16
Number of kids gone camping = 7.
Number of kids who have not gone camping = Total number of kids in the class – Number of kids gone camping
16 – 7 = 9.
Number of kids who have not gone camping = 9
number of kids who have gone camping + number of kids who have not gone camping = total number kids in the class
7 + 9 = 16.
when we reverse the order the expression
9 + 7 = 16.
Explanation:
Given total number kids in the class = 16
Number of kids who have gone camping = 7
From the above calculation
Number of kids who have not gone camping = 9
Total number kids in the class = number of kids who have gone camping + number of kids who have not gone camping
7 + 9 = 16
Changing the order of the addends does not change the sum.
9 + 7 = 16.

Review & Refresh

Question 10.
Which time does not belong with the other three?

Explanation:
Half past 5 means 5:30. In the fig first three images indicate 5:30 where as half past 6 means 6:30.

### Lesson 2.2 Use Doubles

Explore and Grow

Find each sum. How are the equations alike? How are they different?

Explanation:
First two expressions are double. 6 + 6, 7 + 7
In the next  two expression
one is doubles plus 1 expression 6 + 7.
second is doubles minus 1 expression 7 + 6.

Show and Grow

Find the sum. Write the double you used.

Question 1.

4 + 5 = 9
4 + 4 = 8
Explanation:
Doubles plus 1
4 + 5 is equal to 4 + 4 and 1 more.

Question 2.

7 + 6 = 13
7 + 7 = 14
Explanation:
Doubles minus 1
7 + 6 is equal to 1 less than 7 + 7.

Question 3.

Explanation:
Doubles minus 1
6 + 5 is equal to 1 less than 6 + 6.

Question 4.

Explanation:
Doubles plus 1
8 + 9  is equal to 8 + 8 and 1 more.

Apply and Grow: Practice

Question 5.

Explanation:
Doubles plus 1
3 + 4 is equal to 3 + 3 and 1 more

Question 6.

Explanation:
Doubles minus 1
8 + 7 is equal to 1 less than 8 + 8

Question 7.

Explanation:
Doubles plus 1
5 + 6 is equal to 1 less than 5 + 5.

Question 8.

Explanation:
Doubles minus 1
10 +9 is equal to 1 less than 10 + 10.

Question 9.

2 + 3 = 5
2 + 2 = 4
Explanation:
Doubles plus 1
2 + 3 is equal to 2+2 and 1 more.

Question 10.

5 + 4 = 9
5 + 5 = 10
Explanation:
5 + 4 is equal 1 less than 5 + 5.
Doubles minus 1.

Question 11.

6 + 7 = 13
6 + 6 = 12
Explanation:
6 + 7  is equal to 6 + 6 and 1 more.
Doubles plus 1.

Question 12.

9 + 8 = 17
9 + 9 = 18
Explanation:
9 + 8 is equal 1 less than 9 + 9.
Doubles minus 1.

Question 13.
DIG DEEPER!
What double might Newton be thinking?

Given
Sum greater than 4
As per the above information the doubles can be 3 + 3, 4 + 4.
Think and Grow: Modeling Real Life

You make 9 mud pies. Your friend makes 1 fewer than you. How many mud pies do you and your friend make in all?

What double can you use?

Number of mud pies i make = 9
My friend makes 1 fewer mud pies then me = 9- 1 = 8
Total number of Mud pies we both make = 9 + 8 = 17.
Double
9 + 9 = 18.
9 + 8 is 1 less than 9 + 9
Doubles minus 1.

Show and Grow

Question 14.
You score 6 goals. Your friend scores 1 more than you. How many goals do you and your friend score in all?

Number of goals i scored = 6
Number of goals my friend scored = 6 + 1 = 7
Total number of goals we both scored = 6 + 7 = 13.

Question 15.
DIG DEEPER!
You and your friend jump in 13 puddles in all. You jump in 7. How many puddles does your friend jump in?

Total number of puddles me and my friend jumped = 13
Total number of puddles i jumped = 7
Number of puddles my friend jumped = 13 – 7 = 6.
7 + 6 = 13.

### Use Doubles Homework & Practice 2.2

Find the sum. Write the double you used.

Question 1.

4 + 3 = 7
4 + 4 = 8
Explanation:
Doubles minus 1
4 + 3 is equal to 1 less than 4 + 4.
Question 2.

5 + 6 = 11
Doubles 5 + 5 = 10
Explanation:
Doubles plus 1
5 + 6 is equal to 5 + 5 and 1 more

Question 3.

Explanation:
Doubles minus 1
9 + 8 is equal to 1 less than 9 + 9

Question 4.

Explanation:
6 + 7 is equal to 6 + 6 and 1 more.
Doubles plus 1.

Question 5.

8 + 7 = 15
8 + 8 = 16
Explanation:
8 + 7 is equal to 1 less than 8 + 8.
Doubles minus 1.

Question 6.

9 + 10 = 19
9 + 9 = 18
Explanation:
Doubles plus 1
9 + 10 is equal to 9 + 9 and 1 more.

Question 7.
Number Sense
Which doubles can you use to ﬁnd 8 + 9?

To find the expression 8 + 9
8 + 9 is equal to 8 + 8 and 1 more
8 +9 is equal to 1 less than 9 + 9.

Question 8.
Modeling Real Life
You tell 5 jokes. Your friend tells 1 fewer than you. How many jokes do you and your friend tell in all?

Number of jokes i told = 5
Number of jokes my friend told = 5 – 1 = 4
Total number of jokes me and my friend told in together = 5 + 4 = 9
9 jokes together.

Question 9.
Modeling Real Life
Newton paints 3 paw prints. Descartes paints 1 more than Newton. How many paw prints do they paint in all?

Number of paw prints by Newton paints = 3
Number of paw prints by Descartes paints is 1 more than newton = 3 + 1 = 4
Total number of paw prints both Newton and Descartes paint =3 + 4 = 7
Total 7 paw prints.

Review & Refresh

Is the equation true or false?

Question 10.

Question 11.

### Lesson 2.3 Add Three Numbers

Explore and Grow

Find the sums.

What is the same? What is different?
_________________________
_________________________
_________________________

The sum remains same.
Explanation:
Changing the order of addends does not change the sum.
In all the three expressions the sum is same :14

Show and Grow

Circle two addends to add ﬁrst. Write their sum. Then ﬁnd the sum of all three addends.

Question 1.
7 + 3 + 4 = ___

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 14.

Question 2.
1 + 5 + 3 = ___

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 9.

Question 3.
9 + 4 + 4 = ___

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 17.

Question 4.
5 + 2 + 5 = ___

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 12.

Apply and Grow: Practice

Question 5.
3 + 5 + 5 = ___

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 12.

Question 6.
9 + 0 + 7 = ___

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 16.

Question 7.
4 + 2 + 3 = ___

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 9.

Question 8.

Question 9.

Question 10.

Question 11.

9 + 5 + 6 = 20

Question 12.

Question 13.

3 + 7 + 7 = 17
Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 12.

Question 14.
Structure

Think and Grow: Modeling Real Life

You have 6 presents. Newton and Descartes each have 4 presents. How many presents are there in all?

Number of presents with me = 6
Number of presents with Newton = 4
Number of Presents with Descartes = 4
Total Number of presents in all = 6 + 4 + 4 = 14

Show and Grow

Question 15.
You have 8 crayons. Newton and Descartes each have 5 crayons. How many crayons are there in all?

Number of Crayons with me = 8
Number of Crayons with Newton = 5
Number of Crayons with Descartes = 5
Total Number of Crayons in all = 8 + 5 + 5 = 18

Question 16.
You, Newton, and Descartes eat 18 apple slices in all. Newton and Descartes each eat 6 slices. How many apple slices do you eat?

Number of apples slices eaten by Me , Newton and Descartes = 18
Number of apples eaten by Newton =6
Number of apples eaten by Descartes = 6
Total Number of apples eaten by Newton and Descartes = 6 + 6 = 12
Number of apple slices eaten by me = 18 – 12 = 6

Question 17.
A treasure chest has 20 jewels in all. 7 are blue. 6 are green. The rest are red. How many jewels are red?

Number of jewels in Treasure chest = 20
Number of blue jewels = 7
Number of green jewels = 6
Number of blue and green jewels = 7 + 6 = 13
Number of red jewels = 20 – 13 = 7

### Add Three Numbers Homework & Practice 2.3

Circle two addends to add ﬁrst. Write their sum. Then ﬁnd the sum of all three addends.

Question 1.

2 + 5 + 1 = 8

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 8.

Question 2.

6 + 4 + 4 = 14

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 14.

Question 3.

0 + 8 + 7 = 15

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 15.

Question 4.

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 11.

Question 5.

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 13.

Question 6.

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 9.

Question 7.
2 + 8 + 7 = ___

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 17.

Question 8.
9 + 8 + 1 = ___

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 18.

Question 9.
8 + 7 + 5 = ___

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 20.

Question 10.
DIG DEEPER!
Complete the number puzzle so that each branch has a sum of 20.

Explanation :
Sum should be 20
8 + ____ + 7 = 20  so , _____= 20 – 15 = 5
10 + ____ + 10 = 20 so , _______ = 20 – 20 = 0
_____ +  3 + 9 = 20 so , _____ = 20 – 12 = 8
4 + 7 + _____ = 20 so, _____ = 20 – 11 = 9

Question 11.
Modeling Real Life
You, Newton, and Descartes have 17 stampers in all. Newton and Descartes each have 6. How many stampers do you have?
Number of stampers with me , Newton and Descartes = 17
Number of Stampers with Newton = 6
Number of stampers with Descartes = 6
Total Number of stampers with Newton and Descartes = 6 + 6 = 12
Number of Stampers with me = 17 – 12 = 5 Stampers

Question 12.
Make a quick sketch. Complete the sentences.

### Lesson 2.4 Make a 10 to Add

Explore and Grow

Use counters and the ten frames to ﬁnd the sum. How can you make a 10 to solve?

Explanation :
We have 7counters in first table and 6 counters in second table. To make ten counters in first table we should move 3 counters from second table to first table. then,we will have ten counters in first table and 3 in second table. add both 10 + 3 = 13
So, 7 + 6 = 13 .
Show and Grow

Question 1.

Explanation :
To make addend 9 as 10 we should add 1 to the 9 then write addend 7  as  6 + 1 .
then add 9 + 1 we get , 10 and then later add 6 to 10 we get sum , 16 .

Question 2.

Explanation :
To make addend 9 as 10 we should add 1 to the 9 then write addend 5 as  4 + 1 .
then add 9 + 1 we get , 10 and then later add 4 to 10 we get sum , 14 .

Question 3.
6 + 8 = ?
10 + __ = ___
So, 6 + 8 = ___
6 + 8 =
4 + 2 + 8 =
10 + 4 = 14
So, 6 + 8 = 14
Explanation :
To make addend 8 as 10 we should add 2 to the 8 then write addend 6  as  4 + 2 .
then add 8 + 2 we get , 10 and then later add 4 to 10 we get sum , 14 .

Question 4.
7 + 4 = ?
10 + __ = ___
So, 7 + 4 = ___
7 + 4 =
7 + 3 + 1 =
10 + 1 = 11
So, 7 + 4 = 11
Explanation :
To make addend 7 as 10 we should add 3 to the 7 then write addend 4 as  3 + 1 .
then add 7 + 3 we get , 10 and then later add 1 to 10 we get sum , 11 .

Apply and Grow: Practice

Question 5.
2 + 9 = ?
10 + __ = ___
So, 2 + 9 = ___
2 + 9 =
1 + 1 + 9 =
1 + 10 = 11
So, 2 + 9 = 11
Explanation :
To make addend 9 as 10 we should add 1 to the 9 then write addend 2 as  1 + 1 .
then add 9 + 1 we get , 10 and then later add 1 to 10 we get sum , 11 .

Question 6.
8 + 4 = ?
10 + ___ = __
So, 8 + 4 = ___
8 + 4 =
2 + 2 + 8 =
2 + 10 = 12
So, 8 + 4 = 12
Explanation :
To make addend 8 as 10 we should add 2 to the 8 then write addend 4  as  2 + 2 .
then add 2 + 8 we get , 10 and then later add 2 to 10 we get sum , 12 .

Question 7.
9 +6 = ?
10+ ___ = ___
So, 9 + 6 = ___
9 + 6 =
9 + 1 + 5 =
10 + 5 = 15
So, 9 + 6 = 15
Explanation :
To make addend 9 as 10 we should add 1 to the 9 then write addend 6  as  5 + 1 .
then add 9 + 1 we get , 10 and then later add 5 to 10 we get sum , 15 .

Question 8.
7 + 7 = ?
10 + __ = ___
So, 7 + 7 = ___
7 + 7 =
7 + 3 + 4 =
10 + 4 = 14
So, 7 + 7 = 14
Explanation :
To make addend 7 as 10 we should add 3 to the 7 then write addend 7 as  3 + 4 .
then add 7 + 3 we get , 10 and then later add 4 to 10 we get sum , 14 .

Question 9.
6 + 5 = ___
6 + 5 =
6 + 4 + 1 =
10 + 1 = 11
So, 6 + 5 = 11
Explanation :
To make addend 6 as 10 we should add 4 to the 6 then write addend 5  as  4 + 1 .
then add 6 + 4 we get , 10 and then later add 1 to 10 we get sum , 11 .

Question 10.
8 + 9 = ___
8 + 9 =
7 + 1 + 9 =
7 + 10 = 17
So, 8 + 9 = 17
Explanation :
To make addend 9 as 10 we should add 1 to the 9 then write addend 8  as  7 + 1 .
then add 9 + 1 we get , 10 and then later add 7 to 10 we get sum , 17 .

Question 11.
7 + 5 = ___
7 + 5 =
7 + 3 + 2=
10 + 2 = 12
So, 7 + 5 = 12
Explanation :
To make addend 7 as 10 we should add 3 to the 7 then write addend 5 as  3 + 2 .
then add 7 + 3 we get , 10 and then later add 2 to 10 we get sum , 12 .

Question 12.
6 + 6 = ___
6 + 6 =
6 + 4 + 2 =
10 + 2 = 12
So, 6 + 6 = 12
Explanation :
To make addend 6 as 10 we should add 4 to the 6 then write addend 6  as  4 + 2 .
then add 6 + 4 we get , 10 and then later add 2 to 10 we get sum , 12 .

Question 13.
9 + 9 = ___
9 + 9 =
9 + 1 + 8 =
10 + 8 = 18
So, 9 + 9 = 18
Explanation :
To make addend 9 as 10 we should add 1 to the 9 then write addend 9 as  1 + 8 .
then add 9 + 1 we get , 10 and then later add 8 to 10 we get sum , 18 .

Question 14.
8 + 7 = __
8 + 7 =
5 + 2 + 8 =
10 + 5 = 15
So, 8 + 7 = 15
Explanation :
To make addend 8 as 10 we should add 2 to the 8 then write addend 7  as  5 + 2 .
then add 8 + 2 we get , 10 and then later add 5 to 10 we get sum , 15 .

Question 15.
__ = 4 + 7
4 + 7 =
1 + 3 + 7 =
1 + 10 = 11
So, 4 + 7 = 11
Explanation :
To make addend 7 as 10 we should add 3 to the 7 then write addend 4  as  1 + 3 .
then add 3 + 7 we get , 10 and then later add 1 to 10 we get sum , 11 .

Question 16.
__ = 9 + 4
9 + 4 =
9 + 1 + 3 =
10 + 3 = 13
So, 9 + 4 = 13
Explanation :
To make addend 9 as 10 we should add 1 to the 9 then write addend 4  as  1 + 3 .
then add 9 + 1 we get , 10 and then later add 3 to 10 we get sum , 13 .

Question 17.
__ = 8 + 8
8 + 8 =
6 + 2 + 8 =
6 + 10 = 16
So, 8 + 8 = 16
Explanation :
To make addend 8 as 10 we should add 2 to the 8 then write addend 8 as  6 + 2 .
then add 2 + 8 we get , 10 and then later add 6 to 10 we get sum , 16 .

Question 18.
__ = 6 + 8
6 + 8 =
4 + 2 + 8 =
4 + 10 = 14
So, 6 + 8 = 14
Explanation :
To make addend 8 as 10 we should add 2 to the 8 then write addend 6  as  4 + 2 .
then add 2 + 8 we get , 10 and then later add 4 to 10 we get sum , 14 .

Question 19.
Number Sense
How can you make a 10 to ﬁnd 7 + 6?

7 + 6 =
7 + 3 + 3 =
10 + 3 = 13
So, 7 + 6 = 13

7 + 6 =
3 + 4 + 6 =
3 + 10 = 13
So, 7 + 6 = 13
Explanation :
To make addend 7 as 10 we should add 3 to the 7 then write addend 6  as  3 + 3 .
then add 3 + 7 we get , 10 and then later add 3 to 10 we get sum , 13 .
To make addend 6 as 10 we should add 4 to the 6 then write addend 7  as  3 + 4 .
then add 4 + 6 we get , 10 and then later add 3 to 10 we get sum , 13 .

Think and Grow: Modeling Real Life

There are 13 boys and 4 girls in a line. How many girls must join the line so that the numbers of boys and girls are equal?

Number of boys = 13
Number of girls = 4
Number of girls required to add more to become 13 = 4 + _____ = 13 = 13 – 4 = 9
Therefore, Number of girls must join the line so that the numbers of boys and girls are equal = 9 girls .

Show and Grow

Question 20.
There are 16 seals and 7 whales. How many whales must join them so that the numbers of seals and whales are equal?

Number of Seals = 16
Number of Whales = 7
Number of whales must join them so that the numbers of seals and whales are equal = 7 + ____ = 16 = 16 – 7 = 9
Therefore, Number of whales must join them so that the numbers of seals and whales are equal = 9

Question 21.
You and your friend count 15 stars in all. You count 8. How many stars does your friend count?

Number of stars Counted by me and my friend = 15
Number of stars counted by me = 8
Number of stars Counted by my friend = 15 – 8 = 7

Question 22.
There are 17 ﬁsh in a tank. 9 are green. The rest are blue. How many ﬁsh are blue?

Number of Fishes = 17
Number of green Fishes = 9
Number of blue Fishes = 17 – 9 = 8

### Make a 10 to Add Homework & Practice 2.4

Question 1.

Question 2.

Question 3.
7 + 6 = ?
10 + __ = ___
So, 7 + 6 = ___
7 + 6 =
7 + 3 + 3 =
3 + 10 = 13
So, 7 + 6 = 13
Explanation :
To make addend 7 as 10 we should add 3 to the 7 then write addend 6 as  3 + 3 .
then add 3 + 7 we get , 10 and then later add 3 to 10 we get sum , 13 .

Question 4.
8 + 3 = ___
10 + __ = ___
So, 8 + 3 = __
8 + 3=
8 + 2 + 1 =
1 + 10 = 11
So, 8 + 3 = 11
Explanation :
To make addend 8 as 10 we should add 2 to the 8 then write addend 3  as  2 + 1 .
then add 2 + 8 we get , 10 and then later add 1 to 10 we get sum , 11 .

Question 5.
3 + 9 = ___
3 + 9 =
2 + 1 + 9 =
2 + 10 = 12
So, 3 + 9 = 12
Explanation :
To make addend 9 as 10 we should add 1 to the 9 so write addend  3 as  2 + 1 .
then add 1 + 9 we get , 10 and then later add 2 to 10 we get sum , 12 .

Question 6.
8 + 8 = ___
8 + 8 =
8 + 2 + 6 =
10 + 6 = 16
So, 8 + 8 = 16
Explanation :
To make addend 8 as 10 we should add 2 to the 8 so write addend  8 as  2 + 6 .
then add 8 + 2 we get , 10 and then later add 6 to 10 we get sum , 16 .

Question 7.
7 +4 = ___
7 + 4 =
7 + 3 + 1 =
10 + 1 = 11
So, 7 + 4 = 11
Explanation :
To make addend 7 as 10 we should add 3 to the 7 so write addend  4 as  3 + 1 .
then add 7 + 3 we get , 10 and then later add 1 to 10 we get sum , 11 .

Question 8.
4 + 9 = ___
4 + 9 =
3 + 1 + 9 =
10 + 3 = 13
So, 4 + 9 = 13
Explanation :
To make addend 9 as 10 we should add 1 to the 9 so write addend 4 as  3 + 1 .
then add 1 + 9 we get , 10 and then later add 3 to 10 we get sum , 13 .

Question 9.
___ = 6 + 9
6 + 9 =
5 + 1 + 9 =
10 + 5 = 15
So, 10 + 5 = 15
Explanation :
To make addend 9 as 10 we should add 1 to the 9 so write addend  6 as  5 + 1 .
then add 1 + 9 we get , 10 and then later add 5 to 10 we get sum , 15 .

Question 10.
___ = 4 + 8
4 + 8 =
2 + 2 + 8 =
10 + 2 = 12
So, 4 + 8 = 12
Explanation :
To make addend 8 as 10 we should add 2 to the 8 so write addend  4 as  2 + 2 .
then add 8 + 2 we get , 10 and then later add 2 to 10 we get sum , 12 .

Question 11.
__ = 7 + 8
7 + 8 =
5 + 2 + 8 =
10 + 5 = 15
So, 7 + 8 = 15
Explanation :
To make addend 8 as 10 we should add 2 to the 8 so write addend  7 as  5 + 2 .
then add 8 + 2 we get , 10 and then later add 5 to 10 we get sum , 15 .

Question 12.
___ = 9 + 2
9 + 2 =
9 + 1 + 1 =
10 + 1 = 11
So, 9 + 2 = 11
Explanation :
To make addend 9 as 10 we should add 1 to the 9 so write addend 2 as  1 + 1 .
then add 9 + 1 we get , 10 and then later add 1 to 10 we get sum , 11 .

Question 13.
Number Sense
Complete each equation.

Question 14.
Modeling Real Life
There are 12 giraffes and 5 elephants. How many elephants must join them so that the numbers of giraffes and elephants are equal?

Number of Giraffes = 12
Number of Elephants = 5
Number of more elephants must join them so that the numbers of giraffes and elephants are equal = 12 – 5 = 7
Therefore 7 more elephants must join them so that the numbers of giraffes and elephants will be equal .

Question 15.
Modeling Real Life
There are 14 horses on a farm. 7 are brown. The rest are white. How many are white?

Number of Horses = 14
Number of Brown Horses = 7
Number of White Horses = 14 – 7 = 7

Review & Refresh

Compare.

Question 16.

21 < 22
Explanation :
21 is lesser than 22

Question 17.

43 > 34
Explanation :
43 is greater than 34

### Lesson 2.5 Count On and Count Back to Subtract

Explore and Grow

Show two ways to ﬁnd the difference on the number lines.

Explanation :
Count back to find the difference – start at 13 and count back 9.the arrow ending at 4 shows the difference.
Count on to find the difference – Start at 9 and count on to 13.

Show and Grow

Question 1.

Explanation :
Count back to find the difference – start at 11 and count back 5.the arrow ending at 6 shows the difference.

Question 2.

Explanation :
Count back to find the difference – start at 15 and count back 8.the arrow ending at 7 shows the difference.

Question 3.

Explanation :
Count back to find the difference – start at 9 and count back 6.the arrow ending at 3 shows the difference.

Question 4.
16 – 8 = ___

Explanation :
Count back to find the difference – start at 16 and count back 8.the arrow ending at 8 shows the difference.

Apply and Grow: Practice

Question 5.
11 – 8 = ___

Explanation :
Count back to find the difference – start at 11 and count back 8.the arrow ending at 3 shows the difference.

Question 6.
10 – 6 = ___

Explanation :
Count back to find the difference – start at 10 and count back 6. The arrow ending at 4 shows the difference.

Question 7.
14 – 6 = ___

Explanation :
Count back to find the difference – start at 14 and count back 6. The arrow ending at 8 shows the difference.

Question 8.
11 – 4 = ___

Explanation :
Count back to find the difference – start at 11 and count back 4. The arrow ending at 7 shows the difference.

Question 9.
15 – 9 = ___

Explanation :
Count back to find the difference – start at 15 and count back 9. The arrow ending at 6 shows the difference.

Question 10.
16 – 7 = ___

Explanation :
Count back to find the difference – start at 16 and count back 7. The arrow ending at 9 shows the difference.

Question 11.
14 – 9 = ___

Explanation :
Count back to find the difference – start at 14 and count back 9. The arrow ending at 5 shows the difference.

Question 12.
12 – 4 = ___

Explanation :
Count back to find the difference – start at 12 and count back 4. The arrow ending at 8 shows the difference.

Question 13.
10 – 7 = ___

Explanation :
Count back to find the difference – start at 10 and count back 7. The arrow ending at 3 shows the difference.

Question 14.

8 – 4 = 4

Explanation :
Count back to find the difference – start at 8 and count back 4. The arrow ending at 4 shows the difference.

Question 15.

11 – 6 = 5

Explanation :
Count back to find the difference – start at 11 and count back 6. The arrow ending at 5 shows the difference.

Question 16.

18 – 9 = 9

Explanation :
Count back to find the difference – start at 18 and count back 9. The arrow ending at 9 shows the difference.

Question 17.
__ = 9 – 2

Explanation :
Count back to find the difference – start at 9 and count back 2. The arrow ending at 7 shows the difference.

Question 18.
___ = 13 – 5

Explanation :
Count back to find the difference – start at 13 and count back 5. The arrow ending at 8 shows the difference.

Question 19.
__ = 14 – 7

Explanation :
Count back to find the difference – start at 14 and count back 7. The arrow ending at 7 shows the difference.

Question 20.
Structure
What strategy did Newton use to solve? How do you know?

13 – 8 = 5
The Method Used here is Count On to find the difference
Explanation :
It started at 8 and count on to 13 .

Think and Grow: Modeling Real Life

There are 13 backpacks in your classroom. 9 are taken. How many backpacks are left?

Number of backpacks = 13
Number of backpacks taken = 9
Number of backpacks left = 13 – 9 = 4

Explanation :
Count back to find the difference – start at 10 and count back 6. The arrow ending at 4 shows the difference.

Show and Grow

Question 21.
There are 17 trays in a stack. 7 are used. How many trays are left?

Number of trays = 17
Number of used trays = 7
Number of trays left  =17 – 7 = 10
Therefore 10 trays are not used .

Question 22.
DIG DEEPER!

Total Number of songs = 8 + 7 = 15 .

### Count On and Count Back to Subtract Homework & Practice 2.5

Question 1.
7 – 5 = __
Explanation :
Count back to find the difference – start at 7 and count back 5. The arrow ending at 2 shows the difference.

Question 2.
11 – 7 = __

Explanation :
Count back to find the difference – start at 11 and count back 7. The arrow ending at 4 shows the difference.

Question 3.
12 – 5 = __

Explanation :
Count back to find the difference – start at 12 and count back 5. The arrow ending at 7 shows the difference.

Question 4.
17 – 8 = ___

Explanation :
Count back to find the difference – start at 17 and count back 8. The arrow ending at 9 shows the difference.

Question 5.
7 – 2 = ___

Explanation :
Count back to find the difference – start at 7 and count back 2. The arrow ending at 5 shows the difference.

Question 6.
16 – 9 = ___

Explanation :
Count back to find the difference – start at 16 and count back 9. The arrow ending at 5 shows the difference.

Question 7.

9 – 3 = 3

Explanation :
Count back to find the difference – start at 9 and count back 3. The arrow ending at 6 shows the difference.

Question 8.

Explanation :
Count back to find the difference – start at 13 and count back 4. The arrow ending at 9 shows the difference.

Question 9.

12 – 6 = 6

Explanation :
Count back to find the difference – start at 12 and count back 6. The arrow ending at 6 shows the difference.

Question 10.
___ = 10 – 8
10 – 8 = 2

Explanation :
Count back to find the difference – start at 10 and count back 8. The arrow ending at 2 shows the difference.

Question 11.
__ = 8 – 5

Explanation :
Count back to find the difference – start at 11 and count back 5. The arrow ending at 3 shows the difference.

Question 12.
__ = 12 – 3

Explanation :
Count back to find the difference – start at 12 and count back 3. The arrow ending at 9 shows the difference.

Question 13.
DIG DEEPER!
Complete the squares so the differences on the outside are correct.

Explanation :
9 – 4 = 5
7 – 4 = 3
9 – 7 = 2
4 – 4 = 0
All above equations are correct

Question 14.
Modeling Real Life
15 kids are in line to play four square. 7 of them leave. How many kids are left?

Number of kids = 15
Number of kids left the play = 7
Number of kids left to play = 15 – 7 = 8

Question 15.
Modeling Real Life
Newton has 6 pieces of macaroni. Descartes has 15. How many fewer pieces does Newton have than Descartes?

Number of pieces of macaroni with Newton = 6
Number of pieces of macaroni with Descartes = 15
Number of fewer pieces does Newton have than Descartes = 15 – 6 = 9
Therefore , Newton 9 fewer pieces than Descartes .

Question 16.
Precision
Draw more lines to show fourths.

### Lesson 2.6 Relate Addition and Subtraction

Explore and Grow

Write an addition equation. Complete the part-part-whole model to match. Write a related subtraction equation.

Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 9 and 6 to get 15 is the opposite of 15 minus 9, leaving 6 or the opposite of 15 minus 6, leaving 9

Show and Grow

Question 1.
5 + 3 = ___
8 – 5 = ___

5 + 3 = 8
8 – 5 = 3

Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 5 and 3 to get 8 is the opposite of 8 minus 5, leaving 3 or the opposite of 8 minus 3, leaving 5

Question 2.
4 + 7 = __
11 – 4 = ___

4 + 7 = 11
11 – 4 = 7

Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 4 and 7 to get 11 is the opposite of 11 minus 4, leaving 7 or the opposite of 11 minus 7, leaving 4

Question 3.
3 + 9 = ___
12 – 3 = ___
3 + 9 = 12
12 – 3 = 9
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 3 and 9 to get 12 is the opposite of 12 minus 9, leaving 3 or the opposite of 12 minus 3, leaving 9

Question 4.
8 + 6 = ___
14 – 8 = ___
8 + 6 = 14
14 – 8 = 6
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 8 and 6 to get 14 is the opposite of 14 minus 8, leaving 6 or the opposite of 14 minus 6, leaving 8

Question 5.
7 + 8 = ___
15 – 7 = ___
7 + 8 = 15
15 – 7 = 8
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 7 and 8 to get 15 is the opposite of 15 minus 7, leaving 8 or the opposite of 15 minus 8, leaving 7

Question 6.
9 + 9 = ___
18 – 9 = ___
9 + 9 = 18
18 – 9 = 9
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 9 and 9 to get 18 is the opposite of 18 minus 9, leaving 9

Question 7.
4 + 5 = ___
9 – 4 = ___
4 + 5 = 9
9 – 4 = 5
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 4 and 5 to get 9 is the opposite of 9 minus 4, leaving 5 or the opposite of 9 minus 5, leaving 4

Question 8.
5 + 7 = __
12 – 7 = ___
5 + 7 = 12
12 – 7 = 5
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 5 and 7 to get 12 is the opposite of 12 minus 7, leaving 5 or the opposite of 12 minus 5, leaving 7

Question 9.
8 + 8 = ___
16 – 8 = ___
8 + 8 = 16
16 – 8 = 8
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 8 and 8 to get 16 is the opposite of 16 minus 8, leaving 8

Question 10.
5 + 2 = ___
7 – 2 = ___
5 + 2 = 7
7 – 2 = 5
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 5 and 2 to get 7 is the opposite of 7 minus 2, leaving 5 or the opposite of 7 minus 5, leaving 2

Question 11.
4 + 6 = ___
10 – 4 = ___
4 + 6 = 10
10 – 4 = 6
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 4 and 6 to get 10 is the opposite of 10 minus 4, leaving 6 or the opposite of 10 minus 6, leaving 4

Question 12.
2 + 6 = ___
8 – 2 = ___
2 + 6 = 8
8 – 2 = 6
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 2 and 6 to get 8 is the opposite of 8 minus 2, leaving 6 or the opposite of 8 minus 6, leaving 2

Question 13.
7 + 7 = ___
14 – 7 = ___
7 + 7 = 14
14 – 7 = 7
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 7 and 7 to get 14 is the opposite of 14 minus 7, leaving 7

Question 14.
6 + 5 = ___
11 – 6 = ___
6 + 5 = 11
11 – 6 = 5
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 6 and 5 to get 11 is the opposite of 11 minus 5, leaving 6 or the opposite of 11 minus 6, leaving 5

Question 15.
9 + 6 = ___
15 – 6 = __
9 + 6 = 15
15 – 6 = 9
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 9 and 6 to get 15 is the opposite of 15 minus 9, leaving 6 or the opposite of 15 minus 6, leaving 9

Question 16.
3 + 8 = ___
11 – 8 = ___
11 – 3 = __
3 + 8 = 11
11 – 8 = 3
11 – 3 = 8
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 3 and 8 to get 11 is the opposite of 11 minus 8, leaving 3 or the opposite of 11 minus 3, leaving 8

Question 17.
9 + 7 = ___
16 – 9 = ___
16 – 7 = ___
9 + 7 = 16
16 – 9 = 7
16 – 7 = 9
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 9 and 7 to get 16 is the opposite of 16 minus 9, leaving 7 or the opposite of 16 minus 7, leaving 9

Question 18.
8 + 5 = ___
13 – 5 = ___
13 – 8 = ___
8 + 5 = 13
13 – 5 = 8
13 – 8 = 5
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 8 and 5 to get 13 is the opposite of 13 minus 5, leaving 8 or the opposite of 13 minus 8, leaving 5

Question 19.
Structure
Complete the number bond. Write related addition and subtraction equations.

Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 7 and 8 to get 15 is the opposite of 15 minus 7, leaving 8 or the opposite of 15 minus 8, leaving 7

Think and Grow: Modeling Real Life

You have 17 glow sticks. You give away 9 of them. How many glow sticks do you have left?

Number of Glow sticks = 17
Number of glow sticks given away = 9
Number of glow sticks left = 17 – 9 = 8

Show and Grow

Question 20.
A box of sidewalk chalk has 20 pieces. You use 10 of them. How many pieces are not used?

Number of chalks = 20
Number of chalks used = 10
Number of chalks not used = 20 – 10 = 10

Question 21.
There are 7 more butterﬂies than birds. There are 8 birds. How many butterﬂies are there?

Number of birds = 8
Number of butterflies = 7 more butterﬂies than birds = 7 + 8 = 15

Question 22.
A kitchen drawer has 9 fewer forks than spoons. There are 15 spoons. How many forks are there?

Number of spoons = 15
Number of forks = 9 fewer forks than spoons = 15 – 9 = 6

### Relate Addition and Subtraction Homework & Practice 2.6

Question 1.
5 + 5 = ___
10 – 5 = ___

5 + 5 = 10
10 – 5 = 5

Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 5 and 5 to get 10 is the opposite of 10 minus 5, leaving 5

Question 2.
5 + 8 = ___
13 – 8 = ___

5 + 8 = 13
13 – 8 = 5

Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 5 and 8 to get 13 is the opposite of 13 minus 5, leaving  8 or the opposite of 13 minus 8, leaving 4

Question 3.
3 + 4 = ___
7 – 3 = ___
3 + 4 = 7
7 – 3 = 4

Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 3 and 4 to get 7 is the opposite of 7 minus 3, leaving  4 or the opposite of 7 minus 4, leaving 3

Question 4.
8 + 6 = __
14 – 6 = ___
8 + 6 = 14
14 – 6 = 8
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 8 and 6 to get 14 is the opposite of 14 minus 6, leaving 8 or the opposite of 14 minus 8, leaving 6

Question 5.
6 + 6 = ___
12 – 6 = ___
6 + 6 = 12
12 – 6 = 6
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 6 and 6 to get 12 is the opposite of 12 minus 6, leaving 6

Question 6.
5 + 6 = ___
11 – 6 = __
11 – 5 = ___
5 + 6 = 11
11 – 6 = 5
11 – 5 = 6
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 5 and 6 to get 11 is the opposite of 11 minus 6, leaving 5 or the opposite of 11 minus 5, leaving 6

Question 7.
9 + 8 = ___
17 – 9 = ___
17 – 8 = ___
9 + 8 = 17
17 – 9 = 8
17 – 8 = 9
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 9 and 8 to get 17 is the opposite of 17 minus 9, leaving 8 or the opposite of 17 minus 8, leaving 9

Question 8.
7 + 9 = ___
16 – 9 = ___
16 – 7 = ___
7 + 9 = 16
16 – 9 = 7
16 – 7 = 9
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 7 and 9 to get 16 is the opposite of 16 minus 9, leaving 7 or the opposite of 16 minus 7, leaving 9

Question 9.
Number Sense
Find the sums. Write a related subtraction equation for each addition equation.

4 + 9 = 13 and 13 – 4 = 9
7 + 5 = 12 and 12 – 7 = 5
Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 4 and 9 to get 13 is the opposite of 13 minus 4, leaving 9
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 7 and 5 to get 12 is the opposite of 12 minus 7, leaving 5

Question 10.
Modeling Real Life
You have 13 colors of modeling clay. You use 7 of them to make a sculpture. How many colors are not used?

Number of colors with me = 13
Number of colors used = 7
Number of colors not used = 13 – 7 = 6 colors

Question 11.
Modeling Real Life
There are 7 more snails than caterpillars. There are 4 caterpillars. How many snails are there?

Number of caterpillars = 4
Number of snails = 7 more snails than caterpillars.  = 7 + 4 = 11

Question 12.
You have 6 bears. Some are brown. The rest are black. You have more brown bears than black bears. How many brown and black bears can you have?

Show how you know:
Option 1 and Option 4
Explanation :
Number of bears = 6
brown bears > black bears
we cant say the exact number of black or brown bears but as per options we can solve
Option 1 – 5 brown and 1 black satisfy the condition.
Option 4 – 4 brown and 2 black satisfy the condition.
brown bears > black bears

### Lesson 2.7 Get to 10 to Subtract

Explore and Grow

How can you use the number line to ﬁnd the missing number?

Explanation :
Number of linking arrows represent the subtrahend of above equation = 4

Show and Grow

Get to 10 to subtract.

Question 1.

Explanation :
The subtrahend 6 is written as 3 + 3 so that the Minuend 13 is subtracted with 3 to get 10. then 3 is subtracted from 10 , we get difference as 7.

Question 2.

Explanation :
The subtrahend 8 is written as 2 + 6 so that the Minuend 12 is subtracted with 2 to get 10. then 6 is subtracted from 10 , we get difference as 4.

Question 3.
14 – 8 = ?
10 – __ = __
So, 14 – 8 = ___.
14 – 8
14- (4 + 4)
10 – 4 = 6
So, 14 – 8 = 6
Explanation :
The subtrahend 8 is written as 4 + 4 so that the Minuend 14 is subtracted with 4 to get 10. then 4 is subtracted from 10 , we get difference as 6.

Question 4.
16 – 7 = ?
10 – __ = __
So, 16 – 7 = ___
16 – 7
16 – (6 + 1 )
10 – 1= 9
So, 16 – 7 = 9
Explanation :
The subtrahend 7 is written as 6 + 1 so that the Minuend 16 is subtracted with 6 to get 10. then 1 is subtracted from 10 , we get difference as 9.

Apply and Grow: Practice

Get to 10 to subtract.

Question 5.
12 – 6 = ?
10 – __ = __
So, 12 – 6 = __
12 – 6 =
12 – (2 + 4 )
10 – 4 = 6
So, 12 – 6 = 6
Explanation :
The subtrahend 6 is written as 2 + 4 so that the Minuend 12 is subtracted with 2 to get 10. then 4 is subtracted from 10 , we get difference as 6.

Question 6.
13 – 7 = __
10 – __ = __
So, 13 – 7 = ___
13 – 7 =
13 – (3 + 4)
10 – 4 = 6
So, 13 – 7 = 6
Explanation :
The subtrahend 7 is written as 3 + 4 so that the Minuend 13 is subtracted with 3 to get 10. then 4 is subtracted from 10 , we get difference as 6.

Question 7.
15 – 9 = ?
10 – __ = ___
So, 15 – 9 = ___
15 – 9 =
15 – (5 + 4)
10 – 4 = 6
So, 15 – 9 = 6
Explanation :
The subtrahend 9 is written as 5 + 4 so that the Minuend 15 is subtracted with 5 to get 10. then 4 is subtracted from 10 , we get difference as 6.

Question 8.
14 – 6 = ?
10 – __ = __
So, 14 – 6 = __
14 – 6 =
14 – ( 4 + 2 )
10 – 2 = 8
So, 14 – 6 = 8
Explanation :
The subtrahend 6 is written as 4 + 2 so that the Minuend 14 is subtracted with 4 to get 10. then 2 is subtracted from 10 , we get difference as 8.

Question 9.
13 – 8 = ___
13 – 8 =
13 – ( 3 + 5 )
10 – 5 = 5
So, 13 – 8 = 5
Explanation :
The subtrahend 8 is written as 3 + 5 so that the Minuend 13 is subtracted with 3 to get 10. then 5 is subtracted from 10 , we get difference as 5.

Question 10.
12 – 4= ___
12 – 4 =
12 – ( 2 + 2 )
10 – 2 = 8
So, 12 – 4 = 8
Explanation :
The subtrahend 4 is written as 2 + 2 so that the Minuend 12 is subtracted with 2 to get 10. then 2 is subtracted from 10 , we get difference as 8.

Question 11.
17 – 9 = __
17 – 9 =
17 – ( 7 + 2 )
10 – 2 = 8
So, 17 – 9 = 8
Explanation :
The subtrahend 9 is written as 7 + 2 so that the Minuend 17 is subtracted with 7 to get 10. then 2 is subtracted from 10 , we get difference as 8.

Question 12.
15 – 8 = __
15 – 8 =
15 – ( 5 + 3 )
10 – 3 = 7
So, 15 – 8 = 7
Explanation :
The subtrahend 8 is written as 5 + 23 so that the Minuend 15 is subtracted with 5 to get 10. then 3 is subtracted from 10 , we get difference as 7.

Question 13.
12 – 7 = ___
12 – 7 =
12 – ( 2 + 5 )
10 – 5 = 5
So, 12 – 7 = 5
Explanation :
The subtrahend 7 is written as  2 + 5 so that the Minuend 12 is subtracted with 2 to get 10. then 5 is subtracted from 10 , we get difference as 5.

Question 14.
13 – 4 = ___
13 – 4 =
13 – ( 3 + 1 )
10 – 1 = 9
So, 13 – 4 = 9
Explanation :
The subtrahend 4 is written as 3 + 1 so that the Minuend 13 is subtracted with 3 to get 10. then 1 is subtracted from 10 , we get difference as 9.

Question 15.
__ = 12 – 3
12 – 3 =
12 – ( 2 + 1 )
10 – 1 = 9
So, 12 – 3 = 9
Explanation :
The subtrahend 3 is written as 2 + 1 so that the Minuend 12 is subtracted with 2 to get 10. then 1 is subtracted from 10 , we get difference as 9.

Question 16.
__ = 16 – 7
16 – 7 =
16 – ( 6 + 1 )
10 – 1 = 9
So, 16 – 7 = 9
Explanation :
The subtrahend 7 is written as 6 + 1 so that the Minuend 16 is subtracted with 6 to get 10. then 1 is subtracted from 10 , we get difference as 9.

Question 17.
___ = 14 – 9
14 – 9 =
14 – ( 4 + 5 )
10 – 5 = 5
So, 14 – 9 = 5
Explanation :
The subtrahend 9 is written as 4 + 5 so that the Minuend 14 is subtracted with 4 to get 10. then 5 is subtracted from 10 , we get difference as 5.

Question 18.
__ = 12 – 9
12 – 9 =
12 – ( 2 + 7 )
10 – 7 = 3
So, 12 – 9 = 3
Explanation :
The subtrahend 9 is written as 2 + 7 so that the Minuend 12 is subtracted with 2 to get 10. then 7 is subtracted from 10 , we get difference as 3.

Question 19.
Number Sense
How can you get to 10 to ﬁnd 13 −5?

13 – 5 =
13 – ( 3 + 2 )
10 – 2 = 8
So, 13 – 5 = 8
Explanation :
The subtrahend 5 is written as 3+ 2 so that the Minuend 13 is subtracted with 3 to get 10. then 2 is subtracted from 10 , we get difference as 8.

Think and Grow: Modeling Real Life

A ﬁrst-aid kit has 16 bandages. You use 7 of them. How many bandages are left?
Equation:

Number of bandages = 16
Number of used bandages = 7
Number of bandages not used = 16 – 7 = 9

Show and Grow

Question 20.
There are 12 elephants at a watering hole. 5 of them leave. How many elephants are left?

Number of Elephants at watering hole = 12
Number of Elephants left the watering hole  = 5
Number of Elephants at Watering hole now = 12 – 5 = 7

Question 21.
DIG DEEPER!
There are 17 hot-air balloons on the ground. 5 of them take off at 1:00. 4 more take off at 1:30. How many balloons are still on the ground?

Explain how you found the number of balloons still on the ground.
______________________________________
______________________________________
Number of hot-air balloons on the ground = 17
Number of balloons take off at 1 : 00 = 5
Number of balloons take off at 1 : 30 = 4
Number of balloons left on ground = 17 – 5 – 4 = 8

### Get to 10 to Subtract Homework & Practice 2.7

Get to 10 to subtract

Question 1.

Explanation :
The subtrahend 5 is written as 2+ 3 so that the Minuend 12 is subtracted with 2 to get 10. then 3 is subtracted from 10 , we get difference as 7.

Question 2.

Explanation :
The subtrahend 6 is written as 5+ 1 so that the Minuend 15 is subtracted with 5 to get 10. then 1 is subtracted from 10 , we get difference as 9.

Question 3.
16 – 8 = ?
10 – __ = __
So, 16 – 8 = __
16 – 8
16 – (6 + 2 )
10 – 2 = 8
So, 16 – 8 = 8
Explanation :
The subtrahend 8 is written as 6+ 2 so that the Minuend 16 is subtracted with 6 to get 10. then 2 is subtracted from 10 , we get difference as 8.

Question 4.
13 – 9 = ?
10 – __ = ___
So, 13 – 9 = ___
13 – 9
13 – ( 3 + 6 )
10 – 6 = 4
So, 13 – 9 = 4
Explanation :
The subtrahend 9 is written as 3+ 6 so that the Minuend 13 is subtracted with 3 to get 10. then 6 is subtracted from 10 , we get difference as 4.

Question 5.
14 – 5 ___
14 – 5
14 – (4 + 1 )
10 – 1 = 9
So, 14 – 5 = 9
Explanation :
The subtrahend 5 is written as 4+ 1 so that the Minuend 14 is subtracted with 4 to get 10. then 1 is subtracted from 10 , we get difference as 9.

Question 6.
16 – 7 = ___
16 – 7
16 – (6 + 1 )
10 – 1 = 9
So, 16 – 7 = 9
Explanation :
The subtrahend 7 is written as 6 + 1 so that the Minuend 16 is subtracted with 6 to get 10. then 1 is subtracted from 10 , we get difference as 9.

Question 7.
12 – 8 = __
12 – 8
12 – (2 + 6 )
10 – 6 = 4
So, 12 – 8 = 4
Explanation :
The subtrahend 8 is written as 2+ 6 so that the Minuend 12 is subtracted with 2 to get 10. then 6 is subtracted from 10 , we get difference as 4.

Question 8.
13 – 8 = __
13 – 8
13 – (3 + 5 )
10 – 5 = 5
So, 13 – 8 = 5
Explanation :
The subtrahend 8 is written as 3+ 5 so that the Minuend 13 is subtracted with 3 to get 10. then 5 is subtracted from 10 , we get difference as 5.

Question 9.
__ = 16 – 9
16 – 9
16 – (6 + 3 )
10 – 3 = 7
So, 16 – 9 = 7
Explanation :
The subtrahend 9 is written as 6+ 3 so that the Minuend 16 is subtracted with 6 to get 10. then 3 is subtracted from 10 , we get difference as 7.

Question 10.
___ = 14 – 7
14 – 7
14 – (4 + 3 )
10 – 3 = 7
So, 14 – 7 = 7
Explanation :
The subtrahend 7 is written as 4+ 3 so that the Minuend 14 is subtracted with 4 to get 10. then 3 is subtracted from 10 , we get difference as 7.

Question 11.
__ = 12 – 4
12 – 4
12 – (2 + 2 )
10 – 2 = 8
So, 12 – 4 = 8
Explanation :
The subtrahend 4 is written as 2+ 2 so that the Minuend 12 is subtracted with 2 to get 10. then 2 is subtracted from 10 , we get difference as 8.

Question 12.
___ = 18 – 9
18 – 9
18 – (8 + 1 )
10 – 1 = 9
So, 18 – 9 = 9
Explanation :
The subtrahend 9 is written as 8+ 1 so that the Minuend 18 is subtracted with 8 to get 10. then 1 is subtracted from 10 , we get difference as 9.

Question 13.
Number Sense
Complete each equation.

14 – 8 = 10 – 6
13 – 6 = 10 – 3
15 – 7 = 10 – 2

Question 14.
Modeling Real Life
Descartes has 18 items to sell at a garage sale. He sells 9 of them. How many items does he have left?

Number items with Descartes = 18
Number of items sold = 9
Number of items left for sale = 18 – 9 = 9

Question 15.
DIG DEEPER!
There are 12 penguins. 5 of them leave to ﬁnd food at 5:00. 3 more leave at 5:30. How many penguins are left?

Number of Penguins = 12
Number of penguins left at 5 : 00 = 5
Number of penguins left at 5 : 30 = 3
Remaining Number of penguins = 12 – 5 – 3 = 4

Review & Refresh

Question 16.

19 is a Odd Number .
Explanation :
An odd number is a number that cannot be divided into two equal groups.

Question 17.

12 is a Even number .
Explanation :
An even number is a number that can be divided into two equal groups.  Even numbers end in 2, 4, 6, 8 and 0 regardless of how many digits they have.

### Lesson 2.8 Practice Addition and Subtraction

Explore and Grow

You have 6 yellow buttons and 8 red buttons. Write four equations that describe your buttons.

Number of Yellow buttons = 6
Number of Red buttons = 8
Total Number of buttons = 6 + 8 = 8 + 6 = 14

Show and Grow

Question 1.
3 + 9 = ___
3 + 9 = 12

Question 2.
8 – 6 = ___

2 + 6 = 8
So, 8 – 6 = 2

Question 3.
11 – 4 = ___

7 + 4 = 11
So, 11 – 4 = 7

Question 4.
7 + 7 = __
7 + 7 = 14

Question 5.
9 + 8 = ___
9 + 8 = 17
8 + 8 = 16
Explanation :
9 + 8 is one more than 8 + 8 or 9 + 8
So, 9 + 8 = 17

Question 6.
10 – 7 = __

3 + 7 = 10
So, 10 – 7 = 3

Apply and Grow: Practice

Question 7.

Explanation :
Any number added to 0 gives the number itself.

Question 8.

Question 9.

Question 10.

Question 11.

Question 12.

Explanation :
Any number added to 0 gives the number itself.

Question 13.

Question 14.

Question 15.
__ = 9 + 1
10 = 9 + 1

Question 16.
__ = 4 + 5
9 = 4 + 5

Question 17.
___ = 11 – 8
3 = 11 – 8

3 + 8 = 11
So, 11 – 8 = 3

Question 18.
___ = 9 – 5
4 = 9 – 5

4 + 5 = 9
So, 9 – 5 = 4

Question 19.
__ = 7 + 9
16 = 7 + 9

Question 20.
___ = 7 – 1
6 = 7 – 1

1 + 6 = 7
So, 7 – 1 = 6

Question 21.
___ = 8 + 4
12 = 8 + 4

Question 22.
__ = 14 – 7
7 = 14 – 7

Question 23.
Repeated Reasoning
Find the missing addend. Explain how you solved.

8 + _____ = 13
8 + 5 = 13
Explanation :
To get 13 what should be added to 8
if we add 5 to 8 we get sum 13 .

Think and Grow: Modeling Real Life

Show and Grow

How many more students have brown hair than blonde hair?

Number of students with brown hair = 14
Number of students with black hair = 9
Number of students with blonde hair = 7
Number of more students have brown hair than blonde hair = 14 – 7 = 7
Equation: 14 – 7 = 7
Therefore 7 students more students have brown hair than blonde hair

How many students do not have brown hair?
Equation: 9 + 7

Number of students with out brown hair = ( number of students with blonde and black hair ) = 9 + 7 = 16

Question 24.
How many fewer students have hazel eyes than brown eyes?

Number of students with Blue Color= 8
Number of students with Brown color = 12
Number of students with Hazel Color = 4
Number of students fewer have hazel eyes than brown eyes = 12 – 4 = 8

DIG DEEPER!
How many students do not have brown eyes?

Number of students do not have brown eyes = students with blue color and Hazel color = 8 + 4 = 12

### Practice Addition and Subtraction Homework & Practice 2.8

Question 1.
3 + 5 = ___
3 + 5 = 8

Question 2.
5 + 7 = ___
5 + 7
2 + 3 + 7
= 2 + 10 = 12

Explanation :
To make addend 7 as 10 we should add 3 to the 7 so write addend 5 as  2 + 3 .
then add 3 + 7 we get , 10 and then later add 2 to 10 we get sum , 12 .

Question 3.
13 – 6 = ___

Explanation :
The subtrahend 6 is written as 3+ 3 so that the Minuend 13 is subtracted with 3 to get 10. then 3 is subtracted from 10 , we get difference as 7.

Question 4.
12 – 8 = ___

Explanation :
The subtrahend 8 is written as 2+ 6 so that the Minuend 12 is subtracted with 2 to get 10. then 6 is subtracted from 10 , we get difference as 4.

Question 5.
6 + 0 = __
6 + 0 = 6
Explanation :
Any number added to 0 gives the sum the number itself .

Question 6.
15 – 8 = ___

Explanation :
The subtrahend 8 is written as 5+ 3 so that the Minuend 15 is subtracted with 5 to get 10. then 3 is subtracted from 10 , we get difference as 7.

Question 7.

Question 8.

Question 9.

Question 10.

Explanation :
Any number subtracted with 1 gives the difference of previous number .

Question 11.
___ = 5 + 5
5 + 5 = 10

Question 12.
___ = 3 – 0
3 – 0 = 3
Explanation :
Any number subtracted with 0 gives the difference the number itself .

Question 13.
Number Sense
Which expressions have a sum or difference that is greater than 10?

Question 14.
Modeling Real Life
How many fewer students choose a sandwich than pizza?

Number of students chooses sandwich = 9
Number of students chooses pasta = 4
Number of students chooses pizza = 15
Number of fewer students chooses a sandwich than pizza = 15 – 9 = 4
Therefore 4 fewer students chooses a sandwich than pizza .

DIG DEEPER!
How many students do not choose pizza?

Number of students do not choose pizza = number of students who chooses sandwich and pasta
= 9 + 4 = 13
Therefore, Number of students do not choose pizza = 13

Question 15.
Circle groups of 4. Write a repeated addition equation to match.

Explanation :
Number of birds = 16
Number of groups = 4
Number of birds in each group = 16 ÷ 4 = 4
Therefore, 4 + 4 + 4 + 4 = 16 each group contains 4 birds .

### Lesson 2.9 Problem Solving: Addition and Subtraction

Explore and Grow

Model the story.

You have 5 puzzle pieces. Your friend has 9. How many more pieces does your friend have than you?

Number of puzzles with me = 5
Number of puzzles with my friend = 9
Number of more pieces does my friend have than me = 9 – 5 = 4

Show and Grow

Question 1.
You have 7 more keychains than your friend. You have 15 keychains. How many keychains does your friend have?

Number of key chains with me = 15
Number of key chains with my friend = You have 7 more keychains than your friend = 15 -7 = 8
Explanation :

Apply and Grow: Practice

Question 2.
Some friends are at a community pool. 7 more join them. Now there are 12. How many friends were there to start?

Number of friends at community pool = x
Number of friends joined  = 7
Number of friends now at pool = 15 = x + 7
x + 7 = 15
x = 15 – 7 = 8
Therefore, Number of friends at community pool = 8

Question 3.
Some friends are playing miniature golf. 8 of them leave. There are 6 left. How many friends were there to start?

Number of friends playing golf = x
Number of friends left = 8
Number of friends now playing golf = 6
Number of friends at the start = x- 8 = 6
x= 8+ 6 = 14
Therefore, 14 friends were there to start.

Question 4.
YOU BE THE TEACHER
Newton has 5 fewer ﬁsh than Descartes. Newton has 8 ﬁsh. Your friend uses a bar model to ﬁnd how many ﬁsh Descartes has. Is your friend correct? Explain.

Yes he is correct
Explanation :
Number of fishes with Newton = 8
Number of fishes with Descartes = Newton has 5 fewer ﬁsh than Descartes. that means Descartes 5 more fishes than Newton = 8 + 5 = 13

Think and Grow: Modeling Real Life

15 kids play at a park. 6 of them leave. 9 more kids come to the park. How many kids are at the park now?

Number of kids playing in the park = 15
Number of kids left the park = 6
Number of kids remaining in the park = 15 – 6 = 9
Number of kids joined the park = 9
Total number kids now in the park = 9 + 9 = 18

Question 5.
You have 13 baseball cards. You give 5 away. Then you get 4 more. How many baseball cards do you have now?

Number of base balls cards with me = 13
Number of base balls cards given away = 5
Number of base balls cards remaining with me now = 13 – 5 = 8
Number of base balls cards added = 4
Total Number of base balls cards now = 8 + 4 = 12

Question 6.
DIG DEEPER!
There are 7 adult lions and some cubs in a pride. The pride has 13 lions in all. 3 more cubs are born. How many cubs are in the pride now?

Explain how you solved this problem.

Number of Adults lions = 7
Number of Lions = 13
Number of cubs are more than 3
Number of cubs = 13 – 7 = 6
Therefore, Number of cubs in the pride = 6

### Problem Solving: Addition and Subtraction Homework & Practice 2.9

Question 1.
You have 3 more movies than your friend. You have 10 movies. Your friend has 5 video games. How many movies does your friend have?

Number of movies with me = 10
You have 3 more movies than your friend
Number of movies with my friend = 10 – 3 = 7

Question 2.
Some friends are at a skating rink. 6 more join them. Now there are 11. How many friends were there to start?

Number of Friends at skating rink = x
Number of friends joined = 6
Number of Friends now at skating rink = 11
Number of Friends at skating rink = 11 – 6 = 5
Therefore, 5 friends were there to start

Question 3.
Structure
There are 9 bananas in a bunch. A monkey eats some. There are 5 bananas left. Which picture shows how many bananas the monkey ate?

Number of Bananas = 9
Number of Bananas left = 5
Number of Bananas eaten by Monkey = 9 – 5 = 4
Picture 4 shows 4 Bananas .

Question 4.
Modeling Real Life
You make 4 snow angels and Newton makes 5. Descartes makes 3 more snow angels. How many snow angels are there in all?

Number of snow angels made by me = 4
Number of Snow angels made by Newton = 5
Number of Snow angels made by Descartes = 3
Total Number of Snow angels = 4 + 5 + 3 = 12

Question 5.
Modeling Real Life
Newton has 9 glitter pens. Descartes has 2 fewer than Newton. How many glitter pens do they have in all?

Number of Glitter pens with Newton= 9
Number of Glitter pens with Descartes = Descartes has 2 fewer than Newton = 9 – 2 = 7
Number of Glitter pens in all = 9 + 7 = 16

Review & Refresh

Question 6.
Which two shapes combine to make the shape on the left?

Triangle and semi-circle combine to make the above shape .

### Fluency and Strategies within 20 Performance Task

Question 1.
You and your friend check out books from the library as shown in the table.

a. You have one more adventure book than science books. How many books do you have in all?

Number of History books with me = 5
Number of science books with me = 7
Number of Adventure books with me = one more adventure books than science books = 7 + 1 = 8
Total Number of Books with me N= science + History + Adventure = 7 + 5 + 8 = 20

b. You and your friend have the same number of books. Your friend has more science books than history books. Your friend has an even number of adventure books. How many science books and adventure books does your friend have?

Total Number of books with me = Total Number of books with my friend = 20
Science books > History books
Number of history books with my Friend = 8
Number of Science books with my friend let it be = 10
Number of books remaining = 20 – 8 – 10 = 2
Number of Adventure books = 2 even number
So, all the given conditions are satisfied .

c. How many books do you and your friend have in all that are not history books?

Number of History books with me and my friend = 5 + 8 = 13
Number of Books with me and my friend = 20 + 20 = 40
Number of books in all that are not history books = 40 – 13 = 27 Books.

d. You return 3 books on Monday and 6 books on Thursday. How many books do you have left?

Number of books with me = 20
Number of books returned on Monday = 3
Number of books returned on Thrusday = 6
Number of books left now = 20 – 3 – 6 = 20 – 9 = 11 Books.

### Fluency and Strategies within 20 Activity

To Play:
Place your cube on 0. Roll a die to see how many spaces to move. Write an equation that matches on the Joey Jump Add or Subtract Recording Sheet. Continue until you reach the food and then return to the pouch.

### Fluency and Strategies within 20 Chapter Practice

Question 1.

Explanation :
Changing the Order of addends doesn’t change the sum. The Expressions 7 + 2 and  2 + 7 have the sum  9 .

Question 2.
Number Sense
Complete each equation.

Explanation :
Changing the Order of addends doesn’t change the sum. The Expression a + b = b +a = c ,the sum .

2.2 Use Doubles

Find the sum. Write the double you used.

Question 3.
6 + 5 = ___
___ + ___ = ___
6 + 5 = 11
5 + 5 = 10
Explanation :
Doubles plus 1
6 + 5 is equal to 5 + 5 and 1 more.

Question 4.
8 +9 = ___
___ + ___ = ___
8 + 9 = 17
8 + 8 = 16
Explanation :
Doubles plus 1
8 + 9 is equal to 8 + 8 and 1 more.

Question 5.

Explanation :
Changing the Order of addends doesn’t change the sum. The Expressions 3 + 2 and  2 + 3 have the sum  5 .

Question 6.

Explanation :
Changing the Order of addends doesn’t change the sum. The Expressions 7 + 8 and  8 + 7 have the sum  15 .

Question 7.

Explanation :
Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 14.

Question 8.

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 13.

Question 9.

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 20.

Question 10.
4 + 8 + 8 = ___

Explanation:
Addends are represented in circle and Sum is represented in square.
Gives the sum 20.

Question 10.
Structure

2.4 Make a ten to Add

Question 11.

Explanation :
To make addend 9 as 10 we should add 1 to the 9 so write addend 8 as  1 + 7 .
then add 9 + 1 we get , 10 and then later add 7 to 10 we get sum , 17 .

Question 12.

Explanation :
To make addend 7 as 10 we should add 3 to the 7 so write addend 6 as  3 + 3 .
then add 7 + 3 we get , 10 and then later add 3 to 10 we get sum , 13 .

Question 13.
9 + 6 = ___

Explanation :
To make addend 9 as 10 we should add 1 to the 9 so write addend 6 as  1 + 5 .
then add 9 + 1 we get , 10 and then later add 5 to 10 we get sum , 15 .

Question 14.
4 + 7 = ___

Explanation :
To make addend 4 as 10 we should add 6 to the 4 so write addend 7 as  6 + 1 .
then add 4 + 6 we get , 10 and then later add 1 to 10 we get sum , 11 .

2.5 Count On and Count Back to Subtract

Question 15.
12 – 8 = __

Start at 12 and count back to 8 . The arrow ends at 4 showing the difference . So, 12 – 8 = 4

Start at 8 count on to 12. So, 12 – 8 = 4

Question 16.
14 – 5 = ___

Start at 14 and count back to 5 . The arrow ends at 9 showing the difference . So, 14 – 5 = 9

Start at 5 count on to 14. So, 14 – 5 = 9

Question 17.
17 – 9 = ___

Start at 17 and count back to 9 . The arrow ends at 8 showing the difference . So, 17 – 9 = 8

Start at 9 count on to 17. So, 17 – 9 = 8

Question 18.
7 + 6 = __
13 – 6 = ___
13 – 7 = ___

7 + 6 = 13
13 – 6 = 7
13 – 7 = 6

Explanation :
Addition and subtraction are inverse operations because one operation can “undo” the other operation.
Adding 7 and 6 to get 13 is the opposite of 13 minus 7, leaving 6 or the opposite of 13 minus 6, leaving 7.

2.7 Get to 10 to Subtract

Get to 10 to subtract

Question 19.

Explanation :
The subtrahend 4 is written as 2+ 2 so that the Minuend 12 is subtracted with 2 to get 10. then 2 is subtracted from 10 , we get difference as 8.

Question 20.

Explanation :
The subtrahend 8 is written as 5 + 3 so that the Minuend 15 is subtracted with 5 to get 10. then 3 is subtracted from 10 , we get difference as 7.

Question 21.
16 – 9 = ___
16 – 9 =
16 – ( 6 + 3 )
10 – 3 = 7
So, 16 – 9 = 7
Explanation :
The subtrahend 9 is written as 6+ 3 so that the Minuend 16 is subtracted with 6 to get 10. then 3 is subtracted from 10 , we get difference as 7.

Question 22.
14 – 7 = ___
14 – 7 =
14 – ( 4 + 3 )
10 – 3 = 7
So, 14 – 7 = 7
Explanation :
The subtrahend 7 is written as 4 + 3 so that the Minuend 14 is subtracted with 4 to get 10. then 3 is subtracted from 10 , we get difference as 7.

Question 23.
8 + 3 = ___
8 + 3 = 11

Question 24.
13 – 7 = ___
12 – 4 =
12 – ( 2 + 2 )
10 – 2 = 8
So, 12 – 4 = 8
Explanation :
The subtrahend 5 is written as 2+ 3 so that the Minuend 12 is subtracted with 2 to get 10. then 3 is subtracted from 10 , we get difference as 7.

Question 25.

Question 26.

Question 27.

Question 28.

Question 29.
__ = 5 + 8
5 + 8
3 + 2 + 8
3 + 10 = 13
So, 5 + 8 = 13
Explanation :
To make addend 8 as 10 we should add 2 to the 8 so write addend 5 as  3 + 2 .
then add 2 + 8 we get , 10 and then later add 3 to 10 we get sum , 13 .

Question 30.
__ = 12 – 5
12 – 5 =
12 – ( 2 + 3 )
10 – 3 = 7
So, 12 – 5 = 7
Explanation :
The subtrahend 5 is written as 2+ 3 so that the Minuend 12 is subtracted with 2 to get 10. then 3 is subtracted from 10 , we get difference as 7.

2.9 Problem Solving: Addition and Subtraction

Question 31.
Some friends are playing laser tag. 4 of them leave. There are 8 left. How many friends were there to start?