A computer password contains six characters but does not permit repetition of any characters how many possible passwords are there?

Answer 1

The problem depends on the number of characters you can choose from. You're assigning characters to six different positions. So let's say there are x characters to choose from. Then the number of possible passwords is xP6

Answer 2

N = P(6) = 6! = 720

If you can use all 26 characters from English alfabet then

N = P(26,6) = 26!/20! = 26·25·24·23·22·21 = 165765600 or

N =P(10,6) = 10!/(10-6)! = 10·9·8·7·6·5 = 151200