Have you ever thought why 1 means "one", and 2 means "two"?
The roman numerals are easy to understand but what was the logic behind the phonecian numbers?
It's all about angles !
It's the number of angles.
If one writes the numbers down (see below) on a piece of paper in their older forms, one quickly sees why.
I have marked the angles with "o"s.
No 1 has one angle.
No 2 has two angles.
No 3 has three angles.
and "O" has no angles