50 (fifty) is a positive integer following 49 and preceding 51. Its ordinal form is written "fiftieth" or 50th.


  • 50 is an even composite number.
  • 50 is the number of known Mersenne primes and perfect numbers.
  • 50 is the number of US states.

In googology

In Greek-based number-naming systems, 50 is associated with prefix "pentaconta-", and with prefix "quinquaginti-" in Latin systems.

Currency-related use


It is also the prize for correctly answering the first question in the German game show Wer wird Millionär? in euros.

In chess

There is a fifty-move rule preventing endless chess games.

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