On what number is the metric system based

The metric (or SI) system of units of measure is based on the number 10

and powers of it.

That's why people in Liberia, Burma, and the USA find it so confusing and

hard to learn, and why we stick to our familiar customary system based on

the number 3, 12, 1760, 5280, 16, 2, 4, 128, etc.