1.1.1 The Integer Number Line

Integers

The set of Natural Numbers, represented with the symbol N, is the array of whole numbers starting from 1:

N = {1, 2, 3, 4, …}

If we include 0 (zero) and the negative natural numbers, then we have the set of Integers, represented with the symbol Z:

Z = {… -4, -3, -2, -1, 0, 1, 2, 3, 4 …}

Z can be represented as a 1D line graph, also named the Integer Number Line:

① An integer is a number with no decimal or a whole number.

② The negative integers extend from -1 all the way to -∞.

③ The positive integers extend from +1 up to +∞.

④ 0 (zero) is the only integer neither positive nor negative.