On what number was the mayan number system based ?

Mayan number system is a vigesimal system- that means with a base of 20:

the correct answer is: 20, the Mayan number system is based on the number 20.

This means that a number like 360 is expressed with "18 times 20".

Scientists suggest that number systems based on 10 are inspired by the number of fingers, and number systems based on 20 could be based on fingers counted twice: after the number 10, hands would be turned upside-down.