If the question was posed with a "last" in a mathematical sense, it was posed erroneously. If "last" means "the biggest number to be mentioned by a human being" or any such thing, it should be...
Although a few old books use "whole number" and "natural number" interchangeably, but common usage is that the natural numbers are N = {1, 2, 3, 4, 5, 6, . . . } and the whole numbers are W = {0, 1,...