Before you startAI-drafted · not yet reviewed by an editor
These puzzles reward you for spotting the assumption hiding in plain sight. The obvious answer usually feels right because your mind fills in a detail the problem never stated—such as assuming the snail’s progress is steady, or that “at least one heads” leaves the other coin untouched. The one skill is to pause, list exactly what is given, and ask what you have added that is not given. Then restate the situation in your own terms and solve from there. If your first answer is immediate, it is probably wrong.
Curated
6| # | Title | Difficulty | Tags | |
|---|---|---|---|---|
| 17 | The snail and the wellA gentle trap | Medium | ||
| 22 | At least one headProbability surprise | Medium | ||
| 32 | The Monty Hall problemProbability surprise | Medium | ||
| 33 | The birthday paradoxA likely coincidence | Medium | ||
| 70 | The hundred lockersA surprising pattern | Medium | ||
| 647 | When the hands meetLateral thinking | Medium |