Multiplying my age by 6 then subtracting 6 produces the same result as subtracting 7 from my age then multiplying by 7. How old am I? On my broken calculator with keys + - ÷ x =, the only functional number is 7. How can I get 34 to appear in the readout? A country mints four denominations of coins, in whole numbers of cents. It takes four of these coins to make 21¢, or 24¢, or 25¢, or 26¢. What are the denominations of the coins? These and almost 300 other mathematical puzzles appear in this original collection, devised by world-renowned mathematicians, puzzle creators, and devoted puzzle lovers. A unique puzzle project, it unites the efforts of a dozen authors, including software engineer Andrea Gilbert and Bram Cohen, author of the P2P BitTorrent protocol. Seventeen different types of challenges include 3-D puzzles, chess puzzles, connections, dissections, foldings, geometrical puzzles, logic problems, matchstick puzzles, mazes, moving pieces, number puzzles, put-togethers, strimko, sudoku, visual puzzles, weightings, and word puzzles. The difficulty level of each puzzle is marked by stars, ranging from 2 to 5. Average difficulty level is about 3 stars, promising puzzle enthusiasts many entrancing hours of solving and enjoyment.

Treasury of 300 puzzles features 3D and chess puzzles, connections, dissections, foldings, geometrical and number puzzles, logic problems, matchstick puzzles, mazes, moving pieces, put-togethers, strimkos, sudoku, and visual and word puzzles.

The Code Busters are excited for their class field trip to Angel Island, known as the Ellis Island of the West. One of Mika's ancestors passed through the island's immigration station in the early twentieth century, and Mika thinks he may have left behind some secret messages . . . plus a very special box. But as the Code Busters search for hints from the past, they get caught up in an even bigger secret. Can you crack the code? Test your brain with the Code Busters to see if you have the right stuff to be an ace detective. Answers are in the back, in case you get stuck.

This brand-new puzzle book features 200 logic questions of varying types and difficulty. Mental workout warriors and logic lovers will adore The Everything Book of Logic Puzzles Volume I. You’ll learn ten different kinds of puzzles and how to solve each, with the difficulty slowly increasing from basic to expert as you go along. And every single puzzle is specifically designed to improve memory, vocabulary, and logical reasoning. With increasingly difficult puzzles ranging from introductory to fiendish, and comprehensive answers to explain each puzzle, this book is perfect for puzzlers of all ages and skill levels!

A historical study on the ancient and popular Chinese puzzle game presents more than two thousand all-time tangrams, along with detailed instructions on how to arrange these intriguing puzzle tiles and presenting a variety of special puzzles for the reader to solve. Reprint.