Addition and Subtraction are closely linked.

 

From any subtraction fact, we can normally get another subtraction fact and also two addition facts.

 

Look at the subtraction fact:

 

8 - 3 = 5

 

From this, we can also say that:

 

8 - 5 = 3

 

And we can also write these two addition facts:

 

3 + 5 = 8

5 + 3 = 8

 

This will work for any numbers, even much larger ones.

 

Example

Use the subtraction fact:

 

63 - 27 = 36

 

to work out the values of A, B, C and D.

 

63 - 36 = A

36 + B = 63

27 + C = D

 

Answer

From the subtraction fact:

 

63 - 27 = 36

 

We get the other subtraction fact:

 

63 - 36 = 27

 

and the two addition facts:

 

36 + 27 = 63

27 + 36 = 63

 

So

A = 27

B = 27

C = 36

D = 63

 

Does that make sense?