English Explanatory Dictionary

happy number

English dictionary entry

Meanings

noun
  1. Any number that eventually reaches 1 after some number of iterations of replacing each of its digits by the sum of that digit's squares.

Word forms

happy number happy numbers

Etymology

Popularised by the British mathematician Reginald Allenby in the 1960s, who developed this concept from his daughter, while similar mathematical formulas may have existed earlier in Russia. The number was called "happy" because the iteration to reach 1 was treated like a game of numbers, where reaching 1 is compared to "winning" that game.

Antonyms

sad number unhappy number
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