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So logical

Joe has 16 small square cards, eight black and eight white. On each card is one of the numbers 1 2 3 or 4. There is a 1 on four white cards (W1), a 1 on six black cards (B1), a 2 on two white cards (W2), a 2 on two black cards (B2), a 3 on one white card (W3) and a 4 on one white card (W4). All Penny has to do is place the cards on the grid (above right) with a 1 on a black card in the top right corner, so that the number on each card indicates how many black cards are immediately adjacent to it horizontally and vertically. What cards did Penny place on A B C and D?

WIN £15 will be awarded to the sender of the first correct answer opened on Wednesday 13 October. The Editor’s decision is final. Please send entries to Enigma 1612, ¿ìè¶ÌÊÓƵ, Lacon House, 84 Theobald’s Road, London WC1X 8NS, or to enigma@newscientist.com (please include your postal address).

Answer to 1606 Nightmare!: the number is 53

The winner Tony Griffin of Etobicoke, Ontario, Canada