Why isn't 0 a whole number?

Answer 1

Actually it is. Well, it depends what definition of "whole number" you use. Some definitions include only positive integers, some use it as a synonym of "integers". Therefore, due to this ambiguity, the phrase "whole numbers" would better be avoided in math. Rather, use words or phrases like "integers", "positive integers", or "non-negative integers", to convey the exact meaning, without ambiguity.