Subtraction is made by the operation of -1 defined to be the inverse or opposite of +1, so that for two natural numbers m and n:
- m = n – 1 is the same as n = m + 1.
Given m you get n = m + 1 by adding 1 to m (doing +1), and then you get back m = n – 1 back by subtracting 1 from n (doing -1).
Repeating -1 starting from 0 constructs the negative numbers -1, -2, -3, -4,…,. which together with the natural numbers created by repeating +1, constructs the
- integers .
The negative numbers is a wonderful gift to humanity by the heavens, or simply constructed by the human mind.