Addition to Subtract

Key Concepts

• Add numbers using place value.
• Use properties of operation to find the sum.
• Solve few model questions related to addition by using place

Introduction

Example 1: 

3 – 2 = 1. 

Find 2 + ____ = 3 

Solution: 

3 – 2 = 1. 

So, 2 + 1 = 3. 

Use addition fact to subtract 

Example 2: 

Find 5 – 3.  

To find 5 – 3, you can think: 

The missing number is the same in both equations. 

You know the addition fact. 

3 + 2 = 5 

You also know the subtraction fact. 

5 – 3 = 2 

Example 3: 

Find 15 – 4.  

To find 15 – 4, you can think: 

The missing number is the same in both equations. 

You know the addition fact. 

4 + 11 = 15 

You also know the subtraction fact. 

15 – 4 = 11 

Make a 10 to Subtract

Example 4: 

Find how many more balls are needed to be added to make a ten? 

Solution: 

Add 2 more balls to make a ten. 

Use the ten frames to make a 10 to subtract

Example 5: 

Find 12 – 9 

Solution: 

10 + 2 = 12 

Use the ten frames to make a 10 to subtract (Another way) 

Example 6: 

Find 12 – 9 

Solution: 

10 – 7 = 3  

Exercise

• Think addition and subtract,

6 – 4 =?

4 + ____ = 6

So, 6 – 4 = ____

• Think addition and subtract,

9 – 3 =?

3 + ____ = 9

So, 9 – 3 = ____

• Think addition and subtract,

12 – 4 =?

4 + ____ = 12

So, 12 – 4 = ____

• Complete the addition fact and subtract,

17 – 7 = ____

7 + ____ = 17

• Complete the addition fact and subtract,

14 – 8 = ____

8 + ____ = 14

• Make a ten to subtract by using counters and your workmate.

    11

–   4

______

• Make a ten to subtract by using counters and your workmate.

  16

– 9

______

• Chen had 13 animal stickers. He gave 5 of the stickers away. How many animal stickers does Chen have now?
• Angie bought 13 strawberries. She ate 8 of the strawberries. How many strawberries does Angie have now?

Concept Map

What we have learned

• Use addition fact and subtract two numbers.
• Use the ten frames to make a 10 and subtract two numbers.