No common factors
I chose two two-digit numbers and added them together to get a three-digit number. Each of the three numbers was the product of two primes; all six primes were different.
I then transposed the units digits of my two-digit numbers to create two new numbers (so that if my original numbers had been 12 and 36 my new numbers would have been 16 and 32). The sum of my two new numbers was of course the same as the sum of my two original numbers. The two new numbers and their sum were once again each the product of two primes, the six primes all being different.
Everything said about me is also true of Harry and Tom. Our three-digit numbers were all different, but Harry鈥檚 and Tom鈥檚 three-digit numbers had a factor in common.
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What was my 3-digit number?
WIN 拢15 will be awarded to the sender of the first correct answer opened on Wednesday 24 November 2010. The Editor鈥檚 decision is final. Please send entries to Enigma 1618, 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 1612 So logical: The cards are W1, B1, B1, W1
The winner Sarah Stock of Pentyrch, Cardiff, UK
