Subtraction is one of the six arithmetic operations. It is related to addition as follows: if a+b=c, then c-b=a and c-a=b. Subtraction can also be envisaged as the opposite of addition: if b is added to a to obtain c, then subtract b from c to get back to a.

Subtraction is a natural way to introduce the idea of negative numberss: while it is hard to conceive of having less than no apples, negative numbers arise when someone thinks about subtracting a larger number from a smaller, and they can be shown on a number line.

One way to subtract numbers is to use complements.

The traditional names for the terms of the subtraction

c = a - b 
are difference (c), minuend (a) and subtrahend (b).