Well, you only need one number since the RSA numbers are factors of 2 primes.
Oh Yeah, and you only need every other number, since you know that it isn't prime if it's even.
Also, you don't need to count for 2, because you can check to see if the last number is even, and then the challenge wouldn't be very hard.

$p=<the number>;$r=3;while((p%r)!=0)r+=2; <==Unreadably

**READABLY**
$p=<the number>;
$r=3;
while((p%r)!=0)r+=2;
**READABLY**


Not such a bad solution character count wise.

Just Another Perl Backpacker

In reply to Re: RSA Factoring challenge by Nitsuj
in thread RSA Factoring challenge by one4k4

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.