Mathschallenge.net
A website dedicated to the puzzling world of mathematics and computer programming, with a discussion forum.
Mathschallenge.net
A website dedicated to the puzzling world of mathematics and computer programming.
Paul Hsieh's Puzzles
Logical and mathematical brain teasers, with an indication of difficulty. Hints are provided; solutions are available by email.
Puzzles of Leonid Mochalov
A variety of challenging geometrical and arithmetical puzzles, many with solutions.
Pythabacus
Description and instruction of using the ancient Pythagorean Abacus to do arithmetic.
Sequence Puzzles and Problems
With links to related sites. Compiled by Torsten Sillke.
Storkey: Two Envelope Paradox
A tough but simply defined problem which demonstrates key issues in probability.
The Contest Center
Classic puzzles and riddles requiring only simple logic and elementary math.
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