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Thanks in advanced!

 

 Jun 4, 2020
 #1
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n is the number of things to choose from, 

r is how many of them we choose, and 

   order matters 

 

The exclamation point ! means factorial, i.e., the   

product of an integer and all the integers below it. 

Example:  6!  =  6 • 5 • 4 • 3 • 2 • 1 

 

        n!                  4!            4 • 3 • 2 • 1           24          

    ———–   =   ———–   =   ——–––—–   =   ——–   =   24 

    (n – r)!          (4 – 3)!               1!                    1  

.

 Jun 4, 2020

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