ACIT4330-Page/content/Definitions/Terminology/Countable.md

What is countable?

Natural Numbers

Quite simple

\mathbb{N} = \{ 1, 2, 3, 4, \dots \}

Which you can just add it up every time

Integer Numbers

Z can be countable as you can go

1 \to 0 2 \to 1 3 \to -1 4 \to 2 5 \to -2

and so on...

Here they start at 0, then go 1, -1, 2, -2, etc...

Rational Numbers

They are countable, but it is a lot more work to show