## Numbers and Calender

There were several classes of glyphs in the Maya writing system. The first class is the numeric glyphs. Like us, the Maya wrote their numbers in positional notation. This mouthful of words means that the position of a "digit" dictates its actual numerical value. For example, the digit "7" means seven if its position is at the end of a number, but if it is one position before the end, then it stands for seventy. And if it is two positions before the end, then it is seven hundred. Mathematically, you will see that digit is multiplied by the "base" of 10 raised to the position of the digit: 700 = 7 x 102 70 = 7 x 101 7 = 7 x 100

Likewise, among the Maya, the position of a "digit" also determines the actual value of the digit. However, unlike our system, which is based on powers of 10, the Maya (and Mesoamericans in general) used powers of 20. Also, unlike our system, which has an individual symbol for each digit (0, 1, 2, 3, ...), the Maya only employed three basic symbols: A dot for a value of "one", a bar for a value of "five", and a shell for the value "zero". Arithmetic combinations of these yield "digits" from zero to nineteen. For example, four is represented as four dots, seven is a bar and two dots, and nineteen is three bars and four dots as 3 x 5 + 4 x 1 = 19. Numbers larger than 20 are written via positional notation, like the following example: Closely allied to the number system of the Maya is their incredibly intricate calendar system. The Maya time-keeping involved several interlocking cycles, some of which tracked astronomical events while others seemingly followed abstract time intervals. Similar to other Mesoamerican cultures, the Maya employed a 365-day solar calendar (*jaab'*) and a 260-day ritual cycle (*tzolk'in*). The *jaab'* is divided into 18 "months" of 20 days, plus 5 "unlucky" days at the end called *wayeb'*. The following chart illustrates the signs of *jaab'* solar calendar.