Question

Each character in a password is either a digit [0-9] or lowercase letter [a-z]. How many valid passwords are there with the given restriction(s)? Length is 13. No character repeats.

Answer 1

2310789600

Explanation:

10 digits + 26 letters = 36

₃₆C₁₃ = 2310789600

Hope this helps, although i am not 100 percent sure its right.