Tech WondersPlay

Data & ProbabilityProbability

The 100 Prisoners Riddle

A clever plan turns near-certain death into a 31% chance

A hundred prisoners must each find their own number among 100 boxes, opening only 50. The odds look hopeless. Are they?

You'll find out

  • Why random guessing is hopeless
  • How following numbers beats guessing
  • Why everyone wins or loses together

Why it matters

The riddle came out of research on how computers store and look up data, where linked choices matter.

About 3 min6 interactive slides · 5 questionsLesson 157 · Zone 18

Play this lesson

Free to play in your browser or on iPhone

More in this zone

  1. 154Infinite SeriesAchilles and the TortoiseInfinitely many steps can take finite time
  2. 155Bridge EngineeringSuspension BridgesCables turn huge loads into tension they can handle
  3. 156Recreational MathematicsThe 1089 TrickAny three-digit number leads to the same answer
  4. 158PsychoacousticsWhy Ads Sound LouderTwo sounds at the same volume can feel completely different
  5. 159Computing HistoryThe Women Who Programmed ENIACSix women programmed the first general-purpose electronic computer
  6. 160Language ModelsSame Question, Different AnswerA dial called temperature makes chatbots creative or predictable
  7. 161CryptographyHow Long to Crack It?Every extra character multiplies an attacker's work
  8. 162CybersecurityHow Sites Store Your PasswordA good website never actually knows your password