Turing Machine
Question a computer made of punch cards and deduce its three-digit secret code.
- 1–4 players
- about 20 min
- Some thinking
- Deduction
- Abstract
The goal
Find the one correct three-digit code sooner than anyone else, with fewer questions.
How it plays
- 1The code is three digits from 1 to 5: a blue triangle, a yellow square and a purple circle. There are 4 to 6 verifiers on the table, each checking a single criterion, such as “blue compared with 3”.
- 2Each round you secretly choose a three-digit proposal and stack the three matching punch cards.
- 3Take that stack to verifiers, at most 3 per round. Laid over a verifier's card, the holes show a tick or a cross: whether your number passes that verifier's one criterion.
- 4Note the results. Working out exactly which criterion each verifier is testing is part of the puzzle.
- 5At the end of a round, anyone who feels sure may guess the code.
How you win
A correct guess wins; if several players are right in the same round, the one who asked fewer questions wins. A wrong guess puts you out and the others carry on.
First time?
- Only one code satisfies every verifier at once. That fact alone rules a lot out.
- Before each question, know what a tick and what a cross would eliminate.
- There are millions of puzzles on the official site. Start with the easy ones.
Watch how to play
In EnglishOpen on YouTube