Apurdue.168 net.general utcsrgv!utzoo!decvax!pur-ee!purdue!mab Sat Jan 23 10:57:24 1982 Re: Factorial Query The idea is this: 3! = 2! x 3 2! = 1! x 2 and in general, n! = (n-1)! x n So, if n = 1, then 1! = 0! x 1 But 1! is 1 from the definition, so 0! HAS to be 1 for this relation to hold. Note that this formula breaks down at n=0, because 0! = 1 != (-1)! x 0 regardless of how you define (-1)!, because 0 x anything = 0. But 0! = 1 makes the formula consistant everywhere else. (Oh, yes ... for any other mathematical types, that 0! = 1 is also derivale from the relationship n! = GAMMA(n+1), where GAMMA is the gamma function... but the formula I mentioned above is so much more elegant!!!) Matt Bishop (purdue!mab) ----------------------------------------------------------------- gopher://quux.org/ conversion by John Goerzen of http://communication.ucsd.edu/A-News/ This Usenet Oldnews Archive article may be copied and distributed freely, provided: 1. There is no money collected for the text(s) of the articles. 2. The following notice remains appended to each copy: The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 Bruce Jones, Henry Spencer, David Wiseman.