if upper case and lower case letters are considered as different letters, how many six-letter computer passwords are possible with no repeated letters?
52 letters to choose from 6 letter permutations That is 52P6
$${\left({\frac{{\mathtt{52}}{!}}{({\mathtt{52}}{\mathtt{\,-\,}}{\mathtt{6}}){!}}}\right)} = {\mathtt{14\,658\,134\,400}}$$
