Natural Numbers and Whole Numbers In mathematics, it's sometimes helpful to talk about groups of things, which are called sets. Numbers can be grouped into sets, and a particular number can belong to more than one set.
You probably are familiar with the set of natural numbers, which are also called the counting numbers. These are the numbers 1, 2, 3, and so on—the numbers we use when counting.
The following illustration shows the natural numbers graphed on a number line.
The number line continues in both directions. The set of natural numbers only continues to the right, so you can include 6, 7, and so on, all the way up into the hundreds, thousands, and beyond. You can only show so much on one picture!
When 0 is added to the set of 1, 2, 3, and so on, it forms the set of whole numbers. These are called “whole” because they have no fractional parts. (A trick to help you remember which are natural numbers and which are whole numbers is to think of a “hole,” which can be represented by 0. The whole ("hole") numbers include 0, the natural numbers do not.)
The following illustration shows the whole numbers graphed on the number line.
