Tricky cards
Shown right are two of the cards Joe asked Penny to make for him. Joe specified four colours (A, B, C and D) and Penny could choose any one of them for any of the four areas.
Penny had only made a few cards when she turned one round and noticed that it was the same as the one she had just made. She had assumed that all the cards must be different, so she set about calculating how many different cards made up a full set.
How many cards make up the set?
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WIN 拢15 will be awarded to the sender of the first correct answer opened on Wednesday 10 August. The Editor鈥檚 decision is final. Please send entries to Enigma 1654, New 女生小视频, Lacon House, 84 Theobald鈥檚 Road, London WC1X 8NS, or to enigma@newscientist.com (please include your postal address).
Answer to 1648 Enigmarred: ENEMA represents the number indivisible by 9
The winner Jonathan Darch of Milton Keynes, Buckinghamshire, UK
