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(3): Solution (VB program) by Charlie)

Thanks, Charlie.

I didn't know about this technique. I'll definitely check this out. It will make future programs a lot more concise.

 

Posted by Penny on 2005-01-04 20:03:37