I interpret this as though passwords can have both digits and letters mixed. For instance not only can you have passwords like 4703 and HGLP, but also passwords like these A5H2 and 7J6K, with mixed letters and digits. Therefore, we can use any of 36 characters (26 letters plus 10 digits = 36 characters) (36)(35)(34)(33) = 1,413,720 Edwin