Maya mathematicians, lacking the tables and slide rules of presentday students, probably calculated with counters, grains of maize, or beans, perhaps employing a simple abacus.
Calculations in the Maya calendar can be made with great speed and accuracy with counters, using a year (here called the computing year) of 364 days and its multiples.
Certain tables in the Dresden Codex consist of multiples of the computing year arranged in the vigesimal system and carried by simple additions (the nearest the Maya got to true multiplication) to very high numbers.
The layout of these tables and the arrangement of their accompanying day signs strongly indicate that they were used in calculating the positions of Maya dates.
Certain errors in the inscriptions can best be explained by assuming that the 364day year and its multiples were used to calculate these positions.



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