Enigma 1519: Dominotrix
11 September 2012
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From New Scientist #2681, 8th November 2008 [link]
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 “pips” in each lot sum to a perfect square.
Which dominoes are still lost?