Tile Tris - Tile a spheroid working room aperiodically or periodically. Includes free demo download. Contest Center Cryptarithms - Examples of cryptarithms, with prize competitions for subscribers. The Enigmatic World of Philip Carter - Collection of brain teasers from the author of IQ books. Riddles - A collection of riddles and logic puzzles with solutions. Mathematical Recreations - Detailed exploration of a selection of mathematical topics. Group Games - Animations that develop the theory behind such puzzles as the Rubik cube. SMSU Problem Corner - Math challenges Southwest Missouri State University in three levels of difficulties. Quia! Mathematics Activities - Educational activities for teaching mathematics including concentration, matching, flash cards, word search puzzles, and Java games. Ken Duisenberg's Puzzle of the Week Archives - Challenging puzzles and problems. Sequence Puzzles and Problems - With links to related sites. Compiled by Torsten Sillke. Aha! Puzzles - Puzzles, books, games and tests with designed by Lloyd King, author of "Test Your Creative Thinking". Mathwizz - Interactive math problems for abilities ranging from middle school to university. Algebraic Math Puzzles - A collection of puzzles at high school level. Does not include answers. Brain Teasers by QBrute - Original brain teasers with solutions. The Null Set - Puzzles collected by Guy Kindler, most requiring some undergraduate mathematical knowledge. Some hints are provided. Torus and Klein Bottle Games - Collection of Java-based educational puzzles. Polymorf - Symmetry of Polyhedra - A demonstration of the symmetry and transformational properties of the Platonic and Archimedean solids. iQED! - Lateral puzzles from "Puzzles for the High IQ" author Lloyd King and founder of The Puzzle Wizards SiteRing. Storkey: Two Envelope Paradox - A tough but simply defined problem which demonstrates key issues in probability. Logic Puzzles - Collection of original numerical-logic puzzles. Many are long and difficult, involve sorting and comparing long lists and are intended to be solved using a good spreadsheet program. MatheMajik - Indian site featuring calculation tricks and math puzzles. Mathschallenge.net - A website dedicated to the puzzling world of mathematics and computer programming. The Contest Center - Classic puzzles and riddles requiring only simple logic and elementary math. Free Puzzle Collections - Educational and recreational puzzles for teachers, students and parents. Each puzzle is graded by difficulty and has a hint. Solutions are available to members. Alphametics Page - Compiled by Mike Keith. Examples of various genres. Mixed Up Math - Logic problems, where equations are mixed up. In various formats like boxes, crosses, diagonals, mazes. Free download. Alphametics and Cryptarithms - Puzzles in which letters or symbols are substituted for the digits in an arithmetical operation like addition. Math Puzzles - Logic puzzles and riddles with some solutions. Wu's Riddles - A collection of riddles, puzzles, and technical interview questions, with a discussion forum. Pythabacus - Description and instruction of using the ancient Pythagorean Abacus to do arithmetic. Magic Math Kingdom - Learn math through games and quiz-oriented tutorial. A Primer on Cryptarithmetic - Instructions, examples, references and links. Alien Tiles - Object of puzzle is to try to get color pieces to create certain patterns in cube. Mathproblems.info - Over one hundred and fifty math problems ranging from basic math to differential equations. Scott Kim - Puzzles for web, computers, and print; ambigrams. Paul Hsieh's Puzzles - Logical and mathematical brain teasers, with an indication of difficulty. Hints are provided; solutions are available by email. Math Forum - Resources, problems and forum for teachers and students in mathematics. 15 Puzzle of Sam Lloyd - Play online Sam Lloyd's "15" puzzle The funny story of this game Mathematical implications of this game Some funny logical problems with the 15 game. The Puzzling World of Barry R. Clarke - Brain teasers, articles and puzzles forum. Mr Titen's More Than Math - Mathematics teacher provides puzzles for students. Alphametic Puzzles - Numerous puzzles, links, puzzle solver, and a generator. Nick's Mathematical Puzzles - A collection of puzzles, with hints, solutions, and links to relevant mathematical topics. Archive Creative puzzles - Interactive puzzle archive with descriptions for puzzle construction and a special childrens puzzle page. Mathpuzzle.com - Celebrates math puzzles and mathematical recreations. A+ Math - Interactive math help for K-12 students with flashcards, Math Wordfind, Homework Helper and worksheets. Clever Games for Clever People - Games that interest John Conway including Rim and Traffic Jam. Logicville - Educational puzzles, brain teasers, and word games such as anagrams, cryptograms, alphametics, doublets, tangrams. Polyhedra Links - Pastime and activity links for various geometric patterns, polygons and polyhedra by Jill Britton. BCIT Mathematical Entertainment - Famous mathematical problems, puzzles, facts, games and trivia. MatheMagic - A collection of mathematical puzzles, jokes and articles. Colorful Mathematics - Educational software presents advanced mathematics to K-12 students in a game-oriented approach, using coloring and drawing techniques to illustrate concepts from graph theory and computer science. Perfect Times - Teaches and assesses fluency of multiplication and division tables using online cards. Submit data and compare results. Interactive Mathematics Miscellany and Puzzles - Java-based math resource including articles, puzzles and links. Brain Teasers and Maths Puzzles - Interactive logical and mathematical puzzles with feedback and detailed solutions.