Natural number definition: A natural number is any number

A natural number is any number in the set of positive integers {1, 2, 3,…} and sometimes zero. In some definitions, zero is included as a natural number, while others only include positive integers starting from 1. Most school math uses natural numbers as 1, 2, 3, and so on, without including zero. Definition of Natural Numbers explained with real life illustrated examples. Also learn the facts to easily understand math glossary with fun math worksheet online at SplashLearn. Learn what natural numbers are, how to write them, and their properties. Natural numbers are positive integers from 1 to infinity, used for counting and excluding zero and negative numbers.