Question 285006: how many different 3-letter passwords are possible if no letter can be repeated?
Answer by toidayma(44)   (Show Source):
You can put this solution on YOUR website! Let (xyz) the possible password. Since no letter can be repeated, x <> y <> z.
Now, how many ways to pick a letter for x: 26 (since there are 26 different letters in the alphabet). After picking x, the number of letters left to chose y is: 25. Also, after picking two letters for x and y, there are 24 ways left to pick for z.
So, there are total 26*25*24 possible values of (xyz).
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