The natural numbers were originally used to count things like sheep, without fractions or decimals. If you had a partial sheep, it was recorded as a whole number and carcass. The set of natural numbers is represented by the counting numbers starting from 1 and continuing indefinitely without end.

1. The counting or natural numbers When man first began using numbers, they were used to keep track of things – like sheep. There were no fractions or decimals. If you had 3 ½ sheep you had 3 sheep and 1 carcass! The set of natural numbers = {1, 2, 3, …}