Notes from the underground
Updated 1 August 2024
Favourite puzzles
41. The watermelon
40. Multiple choice
39. Odd one out
38. Water jugs and burning ropes
37. Dominoes on a chessboard
36. Three white hats
35. Four daughters
34. The war veteran
33. Elementary logic
32. Logical fatalism
31. Bertrand’s paradox
30. The ship of Theseus
29. Simpson’s paradox
28. The shadow
27. The missing dollar
26. The two envelope problem
25. Two errors
24. The wheel and the hub
23. Every natural number can be unambiguously described in fourteen words or less
22. The bottle and the cork
21. Proof that unicorns exist
20. The three marbles
19. Chess position
18. Ten statements
17. What position?
16. How many handshakes?
15. Roll a coin
14. Had had
13. How old is Alice?
12. Knockout tournament
11. The gambler’s-fallacy fallacy
10. The biased coin
9. All horses are of the same colour
8. The couple on the bus
7. A million dots
6. The monk
5. Draw a line
4. Why does a mirror?
3. The tribe that favours boys
2. The water lily
1. Matching socks
15. Roll a coin
A coin is rolled halfway around another without slipping as shown:
Close
Smabs Sputzer (1956-2017)
https://www.flickr.com/photos/10413717@N08/6121404461/
Is it now upright or upside down?
Previous → 14. Had had
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