Check Subtraction Calculations by Using Addition

From any addition fact such as

 

1,462 + 3,763 = 5,225

 

we can work out two subtraction facts.

 

Here we get

5,225 - 1,462 = 3,763

and

5,225 - 3,763 = 1,462

 

This is handy because we can use additions to check subtractions.

 

Example 1

Caleb says that

 

5,681 - 1,724 =

3,957

 

Use addition to check if he is right or wrong.

 

Answer

Add:

 

So 3,957 + 1,724 = 5,681

Caleb is right.

 

 

 

Example 2

Dahlia says that

 

6,286 - 2,457 =

4,829

 

Use addition to check if she is right or wrong.

 

Answer

Add:

 

So 4,829 + 2,457 = 7,286 not 6,286

Dahlia is wrong.

 

 

Let's have a go at some questions on this now.