You have three identical bricks and a ruler. How can you determine the length of a brick’s interior diagonal without any calculation?
The Royal Statistical Society has released its Christmas quiz for 2021, a set of 11 puzzles that require general knowledge, logic, lateral thinking, and searching skills, but no specialist mathematical knowledge.
Anyone may enter, individually or in teams of up to five. The top entry will receive £150 in Wiley book vouchers, second place £50 in book vouchers, and the next three entries a puzzle book or board game. And everyone who achieves a score of 50 percent or higher will win a donation to their favorite charity or good cause.
Entries must be received by 21:00 GMT on January 31. See the quiz web page for the rules and some tips for budding solvers.
Mathematician Matthew Scroggs has released this year’s Christmas card for Chalkdust magazine. (Actually I’m late — it’s been out since December 4.)
Solving 14 puzzles will reveal a Christmas-themed picture in this diagram.
By J. Paul Taylor. White to mate in two moves.
A knight’s tour is a series of moves by a chess knight such that it visits each square on the chessboard once. The example above is a “closed” tour because it ends on the square where it started.
This inspired a puzzle posed by Martin Gardner. If we filled a standard chessboard with knights, one on each square, could all 64 of them move simultaneously? The closed knight’s tour shows that they could — they form a long conga line, with each knight vacating a square for the knight behind it to occupy.
Gardner asks: Could the same feat be accomplished on a 5 × 5 chessboard?
For this final episode of the Futility Closet podcast we have eight new lateral thinking puzzles — play along with us as we try to untangle some perplexing situations using yes-or-no questions.
Many of Lewis Carroll’s characters were suggested by fireplace tiles in his Oxford study.
The sources for this week’s puzzles are below. In some cases we’ve included links to further information — these contain spoilers, so don’t click until you’ve listened to the episode:
Puzzle #2 is from listener Diccon Hyatt, who sent this link.
Puzzle #3 is from listener Derek Christie, who sent this link.
Puzzle #4 is from listener Reuben van Selm.
Puzzle #5 is from listener Andy Brice.
Puzzle #6 is from listener Anne Joroch, who sent this link.
Puzzle #7 is from listener Steve Carter and his wife, Ami, inspired by an item in Jim Steinmeyer’s 2006 book The Glorious Deception.
Puzzle #8 is from Agnes Rogers’ 1953 book How Come? A Book of Riddles, sent to us by listener Jon Jerome.
Many thanks to Doug Ross for providing the music for this whole ridiculous enterprise, and for being my brother.
If you have any questions or comments you can reach us at firstname.lastname@example.org. Thanks for listening!
By Joseph Kling. White to mate in two moves.
By T.P. Bull. White to mate in two moves.
By Sam Loyd. What’s the least number of cords you’d have to cut to divide this hammock into two pieces?
A problem from Peter Winkler’s excellent collection Mathematical Puzzles, 2021:
Four bugs live on the four vertices of a regular tetrahedron. One day each bug decides to go for a little walk on the tetrahedron’s surface. After the walk, two of the bugs have returned to their homes, but the other two find that they have switched vertices. Prove that there was some moment when all four bugs lay on the same plane.