Mayan numerals

The ancient Mayan civilization used a vigesimal (base-20) numeral system. The numerals are made up of three symbols; zero (egg shape), one (a dot) and five (a bar). For example, 19 is

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Digits are stacked with the higher significant digits at the top, so

.

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=

would be read as 1 11 in base 20 (one "twenties" and eleven "ones") or decimal 31.

See also: Numeral system