Maya Numerals

Maya numerals are a vigesimal (base-twenty) numeral system used by the Pre-Columbian Maya civilization.

The numerals are made up of three symbols; zero (shell shape), one (a dot) and five (a bar). For example, thirteen is written as three dots in a horizontal row above two horizontal lines stacked above each other.

Read more about Maya Numerals:  Numbers Above 19, Zero, In The Calendar