Date: May 25, 1995 10:31 PM
Author: Michael South
Subject: re: Puzzling Question
Two "reasons" 0! is one:

a) When something is defined by a multiplication formula, the "default value"

of the formula is generally one, just like a sum starts with zero (good intro

or reinforcement for the concept of additive and multiplicative identity). An

"empty product" is generally assumed to have a value of one.

b) The gamma function gives a value of one for 0!. This is a much more

valid "reason" than the last one, since the gamma function can define

the factorial for things other than positive integers. Of course, the

gamma function involves an improper integral, so the situations in which

you could use it would be somewhat limited.

(I just joined this list, so I don't know what level people here are

teaching).

Now a question of my own--is there a place that I can download an

electronic version of the NCTM standards? (Sorry if this is a

frequently asked question, but there were no archives to search to

determine this).

mike