the aztec calendar
This is what an Aztec calendar looks like. The middle of the Aztec calendar is the face of the sun, Tonatiuh, so sometimes, the Aztec calendar is called La Piedra del Sol, or the sun stone. The Aztec calendar has a pointer that has twenty coordinate dots on it. This corresponds to the Day Glyph Ring, which has twenty day glyphs.
The Aztec calendar is read counter clock-wise, so Cipactli, crocodile, is the first glyph, and Xochitli, flower, is the last. The Aztec year has 260 days, most likely because a trecena, which is their equivalent of a week, has 13 days, and their are twenty coordinate points on their calendar, symbolizing twenty weeks. So when the coordinate point one on the pointer reaches Cipactli again, it will have been 260 days.
how to find out what day will correspond to what glyph
For this, you only need to look at the last two digits in the number of days. If the tens digit is an event number, count off the ones digit from Cipactl (because if the tens digit is an even number, that part of the number must be divisible by twenty. So you only have to count the ones digit.
If the the tens digit is odd, you count the ones digit plus ten. For example, if you have the number 95. The closest number smaller than 95 that is divisible by 20 is 80. You would have 15 left. 5(the ones digit)+10(according to the rule) =15, so it would be Quauhtli, or Eagle.
If the the tens digit is odd, you count the ones digit plus ten. For example, if you have the number 95. The closest number smaller than 95 that is divisible by 20 is 80. You would have 15 left. 5(the ones digit)+10(according to the rule) =15, so it would be Quauhtli, or Eagle.