| Here are some bonus recreational mathematics puzzles available only to subscribers to the Dover Math and Science Newsletter. These puzzles are provided by Dick Hess, the author of our newly released Mental Gymnastics: Recreational Mathematics Puzzles. |
| To get the solutions to these puzzles, click on the link at the bottom of the page. |
| Coins in the Dark |
| There are twenty-six coins lying on a table in a totally dark room. Ten are heads and sixteen are tails. In the dark you cannot feel or see if a coin is heads up or tails up but you may move them or turn any of them over. Separate the coins into two groups so that each group has the same number of coins heads up. (No tricks are involved.) |
| Tennis Aces |
| Roddick is playing Federer in the Wimbledon final. Roddick serves aces on six consecutive points during which time Federer does not touch the ball. However, Roddick is still losing the match. What is the precise score in the match? |
| It's All Relative |
| A man points to a woman and says "That woman's mother-in-law and my mother-in-law are mother and daughter (in some order)." Find three ways that the man and woman can be related. |
| Four Coins and Four Weighings |
| Four coins weigh 4, 5, 6, and 7 grams. In four weighings on a simple two-pan balance, rank the coins by weight. |
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| Click here for the solutions to these puzzles |
