In mathematics, the additive inverse of a number a is the number that, when added to a, yields zero. See this Wikipedia article https://en.wikipedia.org/wiki/Additive_inverse A multiplicative inverse or reciprocal for a number x, denoted by 1/x or x−1, is a number which when multiplied by x yields the multiplicative identity, 1. See this Wikipedia article https://en.wikipedia.org/wiki/Multiplicative_inverse