It's easy to determine how many digits you'll have in the resulting number.

I'm a bit puzzled: sure, logarithms let you replace multiplication with addition -- part of the magic of slide rules -- but isn't taking the base-10 log of something typically as much or more labor intensive then doing the multiplication?

For example: 321 * 311 produces five digits, while 321 * 312 produces six digits.

Sure, you could work out that 10 ** 2.5065 * 10 ** 2.493 = 10 ** 4.9995 and thus five digits, while 10 ** 2.5065 * 10 ** 2.494 = 10 ** 5.0005 and thus six, but is that really easier?

In reply to Re: Re: Re: Finding Primes by simonm
in thread Finding Primes by Tommy

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.