eli5 How do decimals and units of area measurement work?

Question

0.9cmx0.9cm = 0.81cm²
9mmx9mm = 81mm²
Do these two numbers equate?

In: 0

Answer 1

Yes.

Metric really is that simple, and obviously the maths you’ve laid out is sensible.

You can think of a 1cm square being made up of a 10 X 10 (i.e. 100) grid of square mm.