 # 16 Puzzles for International Puzzle Day

January 29, 2008 — Ed Pegg Jr, Editor, Wolfram Demonstrations Project

Today (Tuesday, January 29) is International Puzzle Day. To celebrate, here are 16 puzzles from The Wolfram Demonstrations Project.

 Can 27 3×4×5 blocks be placed in a 12×12×12 box? How about 27 a×b×c blocks? Four identical shapes have an area of 64 or 65, depending on their arrangement. How?
 A box gets rolled around on a floor. After 5 topples, how many different places can it be? What is the connection between borders and map coloring?
 A tennis ball is thrown in a lake. What route allows the ball to be retrieved in the shortest time? If a square is divided into the above shapes, how many different ways can the square be made?

 How many squares are in this grid of squares? You have a bag of marshmallows and a microwave. How can you measure the speed of light?
 Where should you stand so that a statue appears to be as large as possible? Can 10 trees be arranged so that there are 5 rows, each containing 4 trees?
 How many ways can 8 queens be placed on a chessboard so that none attack each other? What are the rules for the strange curves found on paper currency?
 Click on a square to change neighboring lights. How can all the lights be turned off? An urn holds 7 good balls, and 20 bad balls. If 5 balls are chosen, what are the odds that 2 will be good?
 Can you completely cover the orange shape with the given set of disks? Can a square be cut into 4 pieces and rearranged into an equilateral triangle?  