{"product_id":"puzzle-box-volume-1-9780486810041","title":"Puzzle Box, Volume 1","description":"\u003ci\u003eMultiplying 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?\u003cbr\u003eOn my broken calculator with keys ] -   x =, the only functional number is 7. How can I get 34 to appear in the readout?\u003cbr\u003eA 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?\u003cbr\u003e\u003c\/i\u003eThese 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. \u003cbr\u003eSeventeen 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.\u003cbr\u003e\u003cbr\u003e\u003cbr\u003e\u003cb\u003eAbout the Author\u003c\/b\u003e\u003cbr\u003ePeter and Serhiy Grabarchuk are part of the Grabarchuk Puzzle Family. Over a period of decades they have produced puzzle books, puzzle apps, interactive puzzles, and more.\u003cbr\u003e","brand":"Dover Publications","offers":[{"title":"Default Title","offer_id":50503425917202,"sku":"9780486810041","price":14.99,"currency_code":"USD","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0831\/4771\/8930\/files\/img_15b5fabf-9e42-4a08-bdd8-263bc84fcf22.jpg?v=1730791077","url":"https:\/\/surprise-castle.myshopify.com\/products\/puzzle-box-volume-1-9780486810041","provider":"Surprise Castle","version":"1.0","type":"link"}