Here is the basic Mayan numbers from 1 to 20, as you would write them. In the video and in the next pictures, you will see how to represent these symbols on the very tip of your fingers. It's some sort of esoteric mudras that are just brilliant for counting.
Using a symbol for zero, allows you to use two hands so in this way you can count until 20 for 20 times! That's how it works with some examples:
With somebody's help...if someone gives you a hand, you can also count together! The first hand counts 20^0=1, the next 20^1=20, the next 20^2=400, the next 20^3=8000 and so on.