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
$5$	$\text{-}5$	$5+(\text{-}5)=0$
$\text{-}21$	$21$	$\text{-}21+21=0$
$0$	$\text{-}0$	$0+(\text{-}0)=0$
$a$	$\text{-}a$	$a+(\text{-}a)=0$
$\text{-}b$	$b$	$\text{-}b+b=0$