FactorialDate: 4/1/96 at 7:14:46 From: Leigh Ausband Subject: Factorial From Mrs. Fields' seventh grade math classes at Robert Smalls Middle School, Beaufort, SC. Dear Dr. Math, What is factorial? For example: 4 factorial. What is it used for? Eric Peevey 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 Check out our web site! http://mathforum.org/dr.math/ |
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