The numbers 1, 2, 3, are called Arabic numerals. They differ from the Roman numerals I, II, III, because of their appearance and the different spelling and also because they have a private computing system, whereby
they can be recognized.
The Arabs have popularized this system. It was previously invented by the Phoenician merchants for their trading accounts.
Why is called '1 'a, '2' two, '3 'three? What logic is this? This is very simple:
Look at the primitive spelling of the numbers and you'll understand their name if you count the corners!
1 has one angle
2 has two angles
3 has three angles
4 has four corners
5 has five corners
6 has six corners
7 has 7 corners
8 has eight corners
9 has nine corners
And the most extraordinary figure and the most intelligent is! ... 0 no corners!