Sunday Times Teaser 2577 – Number Waves
by Graham Smithers
Published: 12 February 2012 (link)
I challenged Sam to find a 9-figure number using all of the digits 1 to 9 such that each digit occupying an even position was equal to the sum of its adjacent digits. (For example, the digit occupying position four would be equal to the sum of the digits occupying positions three and five.) Sam produced a solution that was exactly divisible by its first digit, by its last digit, and by 11. What was his number?