Dominotrix
OUR toddler granddaughter has been staying with us, and she has used our standard set of dominoes (each twice as long as broad) for building castles. Now that she has gone home I have managed to find most of the set, and I can divide these into two unequal lots. Each lot can be arranged into a solid square, and can also be arranged into a closed ring (for example, 6-4#4-2#2-2#2-6). The total number of 鈥減ips鈥� in each lot sum to a perfect square.
Which dominoes are still lost?
拢15 will be awarded to the sender of the first correct answer opened on 10 December. The Editor鈥檚 decision is final. Please send entries to Enigma 1519, 快猫短视频, Lacon House, 84 Theobald鈥檚 Road, London WC1X 8NS, or to enigma@newscientist.com (please include your postal address). The winner of Enigma 1513 is David Collison of Tonbridge, Kent, UK.
Advertisement
Answer to 1513 Two polygons