Question

What should be added to 8 to make the sum of 0

Answer 1

Conceptually, you are asking for the additive inverse of 8. By definition, in fact, the additive inverse of a number
`x` is a number
`y` such that
`x+y=0`

You obtain the additive inverse of a number by switching its sign, so the additive inverse of 8 is -8. In fact, you have

`8+(-8) = 8-8=0`