Addition and Subtracting: Checking Subtractions (2)

From any addition fact such as

1462 + 3763 = 5225

 

we can work out two subtraction facts.

 

Here we get

5225 - 1462 = 3763

and

5225 - 3763 = 1462

 

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

 

 

Example 1

Caleb says that

5681 - 1724 =

3957

 

Use addition to check if he is right or wrong.

 

Answer

Add:

 

So 3957 + 1724 = 5681

Caleb is right.

 

 

Example 2

Dahlia says that

6286 - 2457 =

4829

 

Use addition to check if she is right or wrong.

 

Answer

Add:

 

So 4829 + 2457 = 7286 not 6286

Dahlia is wrong.