20 (number)
20 can been used as a number base. Remnants of this system remain in some European languages, for example in the English “score” (20) and the French “quatre-vingts” (80, literally four groups of twenty). The old (pre-decimal) English monetary system had twenty shillings in a pound. The ancient Mayan numerical system – counting on fingers and toes – was a base 20 or "vigesimal" system.