These types of "back-of-the-envelope" calculations http://en.wikipedia.org/wiki/Fermi_problem keeps the old ticker sharp, and helps in detecting egregiously erroneous statements like grains of rice on a chessboard (2^n grains on square n) covering the earth to great depth, http://keiapl.org/anec/#rice or 2^60 being larger than the # particles in the universe. http://preview.tinyurl.com/cunwsm
For example, having done the calculation (which I probably could have done in my head), I know that the number of particles in the universe is not 10^1000. ----- Original Message ----- From: Jonathan Lettvin <[email protected]> Date: Friday, April 24, 2009 10:42 Subject: Re: [Jprogramming] table of primes to 1,000,000,000 or more To: Programming forum <[email protected]> > I guess my sense of humor is too dry. > I know the godaddy server idea is useless. > But then, calculating a universe > hexagonal close-packed with Hydrogen > struck me as being a bit overboard too. > Just thought I would join in the fun. > > On Fri, Apr 24, 2009 at 12:44 PM, Zsbán Ambrus > <[email protected]> wrote: > > > On Fri, Apr 24, 2009 at 6:40 PM, Zsbán Ambrus > <[email protected]> wrote: > > > The point is, an average home computer can easily test the > primality> > of any one really huge number in a few moments (and > does too when > > > doing public-key cryptography), > > ... > > > The same is true for factorization, > > > > I'm being a bit imprecise here though, because while a usual home > > computer does do primality tests for public-key cryptography, > I do now > > think it performs prime factorizatoin often. > > > > Ambrus ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
