- The additive inverse of 7 is −7, because 7 + (−7) = 0;
- The additive inverse of −0.3 is 0.3, because −0.3 + 0.3 = 0.
Thus by the last example, −(−0.3) = 0.3.
Types of numbers with additive inverses include:
Types of numbers without additive inverses (of the same type) include:
But note that we can construct the integers out of the natural numbers by formally including additive inverses. Thus we can say that natural numbers do have additive inverses, but because these additive inverses are not themselves natural numbers, the set of natural numbers is not closed under taking additive inverses.