6300846559 is such that 6 is divisible by 2; 63, by 3; 630, by 5; 6300, by 7; and, in general, if you take its first N digits, it will be divisible by the N-th prime.
There is only one other such 10 digit number: can you find it?
(In reply to re: A further analysis
So I mis-counted the four digit solutions
I missed a branch of my tree diagram for the seven and eight digit solutions.
Posted by Jer
on 2005-01-04 19:11:40