Question 285006
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).