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Chip-chop

I have a seven-figure number that uses seven consecutive digits in some order. Starting at the left and deleting a digit leaves a six-digit number, then deleting the right-end digit leaves a five-digit number, then deleting the left-hand end digit leaves a four-digit number, and so on, alternating sides until a single digit is left. Looking at the list of seven numbers obtained in this way I see that they are all odd, and that only the six-digit number is divisible by 3 (but not 9). Surprisingly, if I had carried out the process starting by deleting the right-hand end digit and then the left, and so on down to a single digit, all the above facts would still be true.

What number did I start with?

WIN £15 will be awarded to the sender of the first correct answer opened on Wednesday 24 April. The Editor’s decision is final. Please send entries to Enigma 1742, Â鶹´«Ã½, Lacon House, 84 Theobald’s Road, London WC1X 8NS, or to enigma@newscientist.com (please include your postal address).

Answer to 1736 Child’s play: The largest value of SNAP is 9376

The winner Philip Belben of Coalville, Leicestershire, UK