Subject: Sums of digits and other tricks and factor()
From: Stavros Macrakis
Date: Thu, 10 Dec 2009 17:35:56 -0500
The slow part of factoring
8788797887776565343256785434546789796543568097876592 into its prime factors
is not in finding the small factors 2^4*3*799760501, but the big ones
268141679222792839781*853815361070739347909. See
http://en.wikipedia.org/wiki/Integer_factorization for more background.
-s
On Thu, Dec 10, 2009 at 5:29 PM, Richard Hennessy <rich.hennessy at verizon.net
> wrote:
> I have been wondering why factor() is slow on factoring big exact numbers
> that are in the form y/x where x is a big even integer and y is an
> integer. It is easy to tell that factor
> 8788797887776565343256785434546789796543568097876592 is factorable by 2 just
> by looking at the last digit.
>