Categories

Jim Loy's Puzzle Page - Classic and original puzzles.

The Truth Tree's Math and Logic Board - Collection of math and logic puzzles ranging in levels of difficulty.

Dave's Logic Puzzles - Monthly logic puzzles with solving grids.

IBM Research: Ponder This - Monthly logic and math puzzles set by IBM researchers with solutions.

Leisure Ideas: Puzzles - Some mathematical puzzles with answers and/or a hint.

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.]

CrocoPuzzle - Contains print-out and interactive versions. [English and German.]

Mathematical Jigsaw Puzzles - Information on polyominos and square puzzles.

The Eternity Puzzle - Article on how this difficult jigsaw puzzle was solved.

The Two-Envelope Paradox: A Complete Analysis? - Describes aspects of a critical problem and apparent paradox in probability theory.

WU Forums - Discussion board hosted at Berkeley with talk about a variety of solved and unsolved brain teasers.

Tangram Magic Egg - Tangram which creates hundreds of birds including geometry, tasks, solutions and downloads.

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 Riddles of Oscar - Contains riddles and puzzles with solutions.

Monty Hall Game - JavaScript example of the Monty Hall Game. This game demonstrates the real (empirical) affect of statistics.