The number systems of the North American Indians have recently been discussed in detail in two papers in this Monthly [2]. The system of numbers developed by the semi-civilized Maya Indians of Central America is probably the most interesting of all systems developed by the early inhabitants of this continent.

The examples of the number system of the Mayas that have been found, or at least that have been deciphered, deal with the counting of time events or periods, and many authorities are of the opinion that the recording of time series was the sole purpose of their numbers. The records of their chronicles are found as glyphs on the monuments and as written in the codices. These records present two methods of writing numerals, the normal form and the head-variant form. Both forms are essentially the same, and the Mayas were able to express a number as easily by one method as by the other. The head-variant form is found with few exceptions on the monuments, while the normal form is found exclusively in the codices.

In the head-variant form there are distinctive head forms for each of the numbers from 0 to 12 inclusive, while from 13 to 19 inclusive the numbers are written by using the head form for 10 plus the form for whatever unit is needed to make up the desired number.