Mind-Bending Math & GamesCombinatorics

The Party Puzzle

At any party of six, three are all friends or all strangers

Throw a party for six people you've picked completely at random. There's one thing about your guests you can promise before anyone arrives. What?

You'll find out

  • What six guests can never avoid
  • Why five guests can slip through
  • The party size no one can compute

Why it matters

It's the simplest case of a deep idea: in any big enough crowd, network or data set, some pattern is unavoidable.

About 3 min6 interactive slides · 5 questionsLesson 68 · Zone 8

Play this lesson

Free to play in your browser or on iPhone

More in this zone

  1. 64Computer NetworksFinding a RoutePackets cross the planet without anyone knowing the whole map
  2. 65Data AnnotationYou've Been Training AI for FreeThose CAPTCHA traffic lights and crosswalks taught machines to see
  3. 66Pattern PerceptionFaces EverywhereYour brain is so tuned to faces it finds them in plugs and toast
  4. 67SpaceflightSixteen Sunrises a DayThe space station circles Earth every 90 minutes
  5. 69Internet TrafficHalf the Internet Is RobotsNearly half of all web traffic is not human
  6. 70Social EngineeringWould You Plug It In?Nearly half of dropped USB sticks got plugged in
  7. 71AcousticsThe Sonic BoomOutrun your own sound and it piles up into a shock wave
  8. 72Color ScienceThe Missing YellowYour screen shows yellow without a single yellow light