# Additive inverse

### From Conservapedia

The **additive inverse** of a complex or real number x is the number y such that x and y add to equal the additive identity, the number zero. The additive inverse is a function defined for all complex numbers, and is cyclical with period 2 (idempotent). However, for this function to exist in basic mathematics, one must first accept the existence of the negative numbers. This was a large impedence to early mathematics, because early people had difficulty imagining something less than nothing.