Date: 4/2/96 at 4:2:32
From: Doctor Jodi
Subject: Re: Factorial
Hi Eric!
4 factorial is written 4! and means 4*3*2*1
Say you were having a lottery and were picking 4 numbers out of 60 with
no repeats of numbers.
You'd find out the probability of picking a certain 4-number set (in a
certain order) by saying
60 choices for the first number,
59 for the second,
58 for the third,
57 for the fourth.
So there are 60*59*58*57 ordered sets of 4 numbers.
This can also be written as
60!
---
(60-4)!
which will give you 60! divided by 56!
Since the numbers 56 and less divide out, you're left with 60*59*58*57
as the number of ordered sets of 4 lottery numbers that could be drawn
-Doctor Jodi, The Math Forum
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