Where does “不足数” come from?

不足数 (Japanese) comes from Japanese 数, from Middle Chinese 數, from Old Chinese 數.

不足数 (Japanese): deficient number, a number for which the sum of proper divisors is less than that number

Definitions

  1. deficient number, a number for which the sum of proper divisors is less than that number

Ancestry of “不足数”, step by step

不足数 traces back through two separate lines of ancestry.

via Japanese 数

StepLanguageWordMeaning
1Japanese数number; amount; number; several
2Middle Chinese數—
3Old Chinese數—

via Japanese 不足

StepLanguageWordMeaning
1Japanese不足insufficient; unsatisfactory; insufficiency,...
2Middle Chinese不足—
Every word from Old Chinese 數 →Every word from Middle Chinese 數 →Every word from Japanese 数 →