Puzzle Library
Browse our hand-curated puzzles
All Puzzles
27 puzzlesBrowse every puzzle in the library
Starter Puzzles
6 puzzlesPuzzles for new hikers starting out!
Puzzles By Difficulty
Easy
15 puzzlesSingle-insight puzzles accessible with everyday reasoning. One "aha!" moment required.
Medium
9 puzzlesMulti-step puzzles requiring persistence and systematic thinking. High school mathematics sufficient.
Hard
1 puzzleRequires specific techniques like induction, graph theory, or advanced proofs. Multiple interconnected insights needed.
Expert
1 puzzleDeep mathematical reasoning or research-level thinking. Advanced proof techniques and mathematical background required.
Open
1 puzzleCurrently unsolved problems with no known solution. Active areas of mathematical research.
Recommended Puzzles
Two Children 2
You’re talking to a different colleague at work when it comes up in the conversation that he has 2 children. “What genders are they?” you ask again. “Well, the...
Chain Link 2
An apprentice is working for you, the village’s master blacksmith, for 21 days. For payment, you have agreed to give him a gold chain with 21 links, one link...
Traversing the Hypercube
Ossarion-429 is a multi-dimensional being travelling across hypercubes of various dimensions. Bored and having nothing else to do, he wonders to himself if...
The Keyboard Prank
Anne comes into the office to find that her co-workers had played a prank on her. The keycaps on her keyboard had been shuffled such that if she types out a...
100, 10, 1
Your friend, Cole, shows you his first attempt at programming: a calculator that takes in a binary sequence and does an arbitrary computation on it: If the...