Forty Number Names
Base-10 won in Europe, but twelves, twenties and sixties are still embedded in the words, the clock and the marketplace.
A counting system has two separate parts: the words a language speaks and the notation it writes. English speaks a decimal system and writes a positional one; neither is the only possibility, and both carry borrowed pieces of older systems.
Non-positional notation gives every sign a fixed value: in Roman numerals X is ten wherever it stands, and the number is read by adding and subtracting signs. Positional notation gives a digit a value by its place — the 4 in 40 means four tens — and it works only because zero holds empty places.
Base-10 spread with the ten fingers and now dominates both speech and writing. But base-12 runs through the dozen and the gross, through twelve inches in a foot and twelve months in a year; twelve's wealth of divisors — two, three, four, six — made it a trader's favourite.
Base-20, counting on fingers and toes, survives in words. French names eighty quatre-vingts, four twenties; Danish builds fifty to ninety on twenties; traditional Welsh calls forty deugain, two twenties; and English once counted in scores, as four score and seven still records.
Base-60 came from Babylonian astronomy and never left: sixty seconds to the minute, sixty minutes to the hour and to the degree, three hundred and sixty degrees in the circle. Sixty divides by two, three, four, five, six, ten, twelve, fifteen, twenty and thirty — a calculator's base, three thousand years early.
The lesson for number names is that words outlive systems. English is a decimal language that still says eleven and twelve like a duodecimal fossil, keeps score and dozen in daily use, and sets its clocks by sixty. Forty sits inside that layered inheritance: a decimal word, spelled the way a thousand years of speech left it.
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