I came across this entry in wwwjdic: 九百, くひゃく (arch) (derog) fool; idiot Is there a fun story explaining how "900" = "fool"?

1 Answer 1


First you need a little background on old Japanese currency. Back in the Edo period, a 文{もん} was the lowest denominator of currency. A 貫{かん} is a weight measurement (3.75 kg), but is also the weight of 1000 文, which were stringed together to make 10 rolls of 100 coins and those rolls themselves would be used in payment.

九百 comes from 九百文, which is 100 文 short of a 貫. So it is inferring that the person is lacking intelligence, though from my research I can't tell if the phrase is literal (cannot properly count and therefore a fool) or metaphorical (likening the person to a 貫short 100 文).

Incidentally, there is a similar saying in English: "a few cents short of a dollar." This one is definitely used metaphorically, meaning the person is not "all there".

  • Cool, thanks for the explanation!
    – Ned Reif
    Commented Aug 8, 2020 at 6:14

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