The additive inverse of a number is another number such that their sum equals 0. If y is the additive inverse of x, then the following equation holds true.

Given a number, its additive inverse — also called opposite number — can be found by changing the sign. Some examples of additive inverses are listed in the table.

Number	Additive Inverse	Sum
5	- 5	5+(- 5)=0
- 21	21	- 21+21=0
0	- 0	0+(- 0)=0
a	- a	a+(- a)=0
- b	b	- b+b=0