NOTE: **use Perl;** is on undef hiatus. You can read content, but you can't post it. More info will be forthcoming forthcomingly.

##
All the Perl that's Practical to Extract and Report

Stories, comments, journals, and other submissions on use Perl; are Copyright 1998-2006, their respective owners.

## The answer has to be divisible by 9 (Score:1)

The sum of the digits of a number mod 9 is always the number mod 9. The sum of the digits of 2*$n and 3*$n is the same, which means that mod 9, 2*$n and 3*$n are the same, which means that $n is 0 mod 9, so $n is divisible by 9.

This should improve your speed by a factor of 3. :-)

Reply to This## Re: (Score:1)