SOLUTION: This was an extra credit question that nobody knew how to answer. We have not covered permutations and could find nothing about it our books. Please help: How many permutation

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Question 63762: This was an extra credit question that nobody knew how to answer. We have not covered permutations and could find nothing about it our books. Please help:
How many permutations of the word PRODUCT are there, if all the letters are used without repetition.
Answer by joyofmath(189) (Show Source):
You can put this solution on YOUR website!
How many permutations of the word PRODUCT are there, if all the letters are used without repetition.

There are 7*6*5*4*3*2*1 = 5040 permutations of the letters in PRODUCT. Here's why:
There are 7 ways to pick the first letter, 6 ways to pick the second letter since one letter is already picked, 5 ways to pick the third letter, and so on.
By the way, 7*6*5*4*3*2*1 is written as 7! and called 7 factorial.