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:
Some Properties of Integers
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.