The Set of Integer Numbers Z

During medieval times, there came the time where we went deeper into the how and why of everything. This includes mathematics.

The number zero was created as a concept, and so were negative numbers too.

It immediately follows that the set of Natural Numbers N is a Subset of the Integer Numbers:

We now have Z, the set of Integer numbers.
All negative and positive integers, including zero.

Next: The Rational Number Set Q