The Maya left evidence of a highly developed understanding of arithmetic, calendars, and astronomy, which was certainly as sophisticated as contemporary civilizations elsewhere in the world. By the end of the Late Pre-Classic Maya time period (400 BCE – 100 CE), they were using a positional number system which employed only three symbols: a figure resembling a cowry shell representing 0, a dot for 1, and a horizontal bar for five. The number 0 appeared as:
and the numbers 1 to 19 inclusive appeared as:
Numbers larger than 19 were written vertically, employing a vigesimal (base 20) system. For example, the numbers 43, 354, and 220 were written as follows.
The concept of a zero placeholder first occurred among the Olmec, the mother of all Mesoamerican civilizations. By contrast, an ancient Middle Eastern civilization, the Babylonians employed two symbols in a sexagesimal (base 60) system. Without a zero placeholder, though, they did not have the means to make a distinction, the way we do, between numbers such as 6 and 60 (or, in their case, 6 and 6 x 60 = 360). They used, instead, the relative size and spacing of symbols as well as the context to deal with such ambiguities.
The Maya used a modified or quasi-vigesimal number system, in which the value of the third place was 360 instead of 400, for calendric purposes.
Some authors claim that the Maya employed a pure vigesimal system for non-calendric purposes; however, all extant evidence of large numbers relates to the calendar.