Puzzle Box, Volume 1

Multiplyingmyageby6thensubtracting6producesthesameresultassubtracting7frommyagethenmultiplyingby7.HowoldamI?Onmybrokencalculatorwithkeys+-÷x=,theonlyfunctionalnumberis7.HowcanIget34toappearinthereadout?Acountrymintsfourdenominationsofcoins,inwholenumbersofcents.Ittakesfourofthesecoinstomake21¢,or24¢,or25¢,or26¢.Whatarethedenominationsofthecoins?Theseandalmost300othermathematicalpuzzlesappearinthisoriginalcollection,devisedbyworld-renownedmathematicians,puzzlecreators,anddevotedpuzzlelovers.Auniquepuzzleproject,itunitestheeffortsofadozenauthors,includingsoftwareengineerAndreaGilbertandBramCohen,authoroftheP2PBitTorrentprotocol.Seventeendifferenttypesofchallengesinclude3-Dpuzzles,chesspuzzles,connections,dissections,foldings,geometricalpuzzles,logicproblems,matchstickpuzzles,mazes,movingpieces,numberpuzzles,put-togethers,strimko,sudoku,visualpuzzles,weightings,andwordpuzzles.Thedifficultylevelofeachpuzzleismarkedbystars,rangingfrom2to5.Averagedifficultylevelisabout3stars,promisingpuzzleenthusiastsmanyentrancinghoursofsolvingandenjoyment.