The Mayan culture flourished in the Yucatan peninsula of present day Mexico. From about 2000BC a civilisation was built up in the region which reached its high point around 250AD to 900AD.
Most of the documents relating to this period were destroyed by a zealous Spanish monk, but some original texts survive as do the writings of the monk. Later, perhaps regretting his actions, he wrote down some of what he had learned from the Mayans.
The religion of the Mayans was centred around astronomy and to calculate astronomical data they invented a number system. This was far more sophisticated than the clumsy Roman system in use in Europe at the time.
It was based on 20 (no doubt it developed from counting on the 20 fingers and toes). Consider the number 32 for example. In Roman script, this is written, XXXII
and this stands for 10+10+10+1+1.
We would write this in the form, 32 which stands for 3.10 + 2.
The Mayans would write it in the form (using their symbols) 1(12)
which is 1.20 + 12.
The Mayans used only three symbols - a dot, a bar and a shell shaped symbol used for zero. Again the use of zero was a sophistication not known in Europe during this period.
The Mayans wrote their numbers vertically rather than horizontally. This made adding and subtracting far easier; however it seems unlikely that they ever used multiplication or division.