Twenty as a Rounded Quantity

Beyond its role as a counting base, twenty functions in scripture and law mostly as a round threshold: the age of accountability, the price in shekels, the span of a notable service. It lacks the dense symbolic freight of twelve or seven, and much of what attaches to it is arithmetical, the product of four and five, the double of ten, rather than mythic. The Maya vigesimal calendar is the great exception, where twenty is genuinely structural, the number of named days whose interlock with the number thirteen generates the two-hundred-and-sixty-day ritual round. Elsewhere twenty is a convenient large-ish round number, the sort reached for when a count is meant to sound substantial without being exact.

The Maya vigesimal calendar already described is not the only base-twenty counting system on record: several West African and Mesoamerican language families independently developed twenty-based counting, generally attributed to the practical habit of counting fingers and toes together, and traces survive well beyond French quatre-vingts, Welsh and Danish both retain vigesimal remnants in their number words for multiples of twenty, a scattered but genuine linguistic fossil of a counting base older than the decimal system that eventually displaced it almost everywhere.