TechInterview (Popularity: )

Answers to technical interview questions, programming problems, and brain teasers.

Quick Logic Puzzles (Popularity: )

Use the clues provided to deduce the correct sequence of numbers in the hidden code.

The Truth Tree's Math and Logic Board (Popularity: )

Collection of math and logic puzzles ranging in levels of difficulty.

Mathematical Jigsaw Puzzles (Popularity: )

Information on polyominos and square puzzles.

The Monty Hall Problem (Popularity: )

A probability theory puzzle with solutions. [English and German.]

IBM Research: Ponder This (Popularity: )

Monthly logic and math puzzles set by IBM researchers with solutions.

Two Envelope Paradox - Solution (Popularity: )

Claims that the two envelope paradox comes from the incorrect use of probabilities.

Monty Hall Game (Popularity: )

JavaScript example of the Monty Hall Game. This game demonstrates the real (empirical) affect of statistics. [Does not display correctly in all browsers.]

Perplexus (Popularity: )

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, ...

Leisure Ideas: Puzzles (Popularity: )

Some mathematical puzzles with answers and/or a hint.

Jim Loy's Puzzle Page (Popularity: )

Classic and original puzzles.

WU Forums (Popularity: )

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

The Puzzles of Oscar (Popularity: )

Contains puzzles and games with solutions.

CellFighter (Popularity: )

Shareware game based around an extension of the game of life.

PuzzlePicnic (Popularity: )

A place to do puzzles and relax, but also a place where puzzle solvers and puzzle makers meet, entertain and challenge one another.