Θ Games: Puzzles: Brain_Teasers: Mathematical

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TechInterview Answers to technical interview questions, programming problems, and brain teasers.
Perplexus A forum and collection of brain teasers, logic problems, math problems, paradoxes, science games, probability, riddles, and geometric shapes. The puzzles are searchable and categorized, most have solutions.
The Monty Hall Problem A probability theory puzzle with solutions. [English and German.]
Mathematical Jigsaw Puzzles Information on polyominos and square puzzles.
WU Forums Discussion board hosted at Berkeley with talk about a variety of solved and unsolved brain teasers.
Two Envelope Paradox - Solution Claims that the two envelope paradox comes from the incorrect use of probabilities.
Quick Logic Puzzles Use the clues provided to deduce the correct sequence of numbers in the hidden code.
The Puzzles of Oscar Contains puzzles and games with solutions.
Monty Hall Game JavaScript example of the Monty Hall Game. This game demonstrates the real (empirical) affect of statistics. [Does not display correctly in all browsers.]
Leisure Ideas: Puzzles Some mathematical puzzles with answers and/or a hint.
CellFighter Shareware game based around an extension of the game of life.
Kakuro-san Providing graded Kakuro puzzles every day, plus old puzzles.
IBM Research: Ponder This Monthly logic and math puzzles set by IBM researchers with solutions.