Having trouble with algebra

Question

Shen is choosing a 3 letter password from the letters A B C D E...the password cant have the same letter in it...how many passwords are possible

Answer 1

Letters available A B C D E

Let's say the password is BDE,

When choosing the 1st letter i.e. B there are 5 choices (A,B,C,D,E)

When choosing the 2nd letter i.e. D there are 4 choices (A,C,D,E) since B is already chosen

When choosing the 3rd letter i.e. E there are 3 choices (A,C,E) since B & D are already chosen

So the number of ways a 3 letter non-repeating password can be created is 5x4x3 = 60

Answer 2

4*3*2 = 24 <-- four choices for 1st letter, 3 choices for 2nd letter, 2 choices for 3rd letter

4 pick 3 = 4! / (4-3)! = 4! / 1! = 4! = 24