Zero

The notion of zero appears to have come later after the development of the natural numbers. The first zero symbol devised is attributed to the ancient Babylonians. Nothing as a number was at first a difficult concept to grasp. The number zero can be used in numerical identity. A number plus zero is the same number and a number minus zero is the same number. Zero multiplied times any number is zero. In one way zero is different from all the other numbers in that a number cannot be divided by zero, or the answer is undefined. In this way zero is the first existential number conceived of by humans. The set of natural numbers and zero are all within the set of integers and the set of real numbers.

The natural numbers and zero are 0, 1, 2, 3, 4, 5 . . .