In order to have my puzzle well stated let us define the concept of Down/Across Addition.
For that we use the following example :
John Abreu (email) is the author of the above puzzle.
I've got this from rec.puzzles
There is a 9-digit number in which the digits 1 through 9 appear exactly once.
If you only take the first N digits from the left, the number you're left with is
divisible by that same value N. What is this unique number ?
If you like such puzzles please try to contribute to The Nine Digits Page
This problem was found by Stan Wagon in Leningrad Mathematical Olympiads, 1987-1991,
MathPro Press, pp. 7, 62 and was sent to me by John Abreu.
What is the greatest integer so that each of its interior digits is less than the average of its neighbors ?
The answer is surprise surprise... a palindrome !
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