# Counting numbers

Counting numbers (also called whole number or natural numbers) are those used to count physical objects in the real world, such as

0, 1, 2, 3, 4 .....
They are integers that can be zero or positive. They assume that the things being counted are not divisible. So we can have 4 cars, but never 3½ cars.

They are not negative because, when counting things in the real world, the notion of having less than none of them makes no sense. Zero is commonly accepted as one of the counting numbers, but there is no complete agreement about this.

Formally, counting numbers are the set of all non-negative integers.

Counting numbers are also called cardinal numbers.

## Statistics can confuse you

You may have heard something like "the average household has 1.8 children". Obviously, every family has a whole number of children. The average is found by adding up all the children and dividing by the number of households. Once you do that division you no longer have a counting number. That result is a statistic and is actually a real number - one that can have fractional parts.