Permutations
posted by Tifini .
A valid password on a Web site contains 3 letters (AZ, 26 total), followed by 3 digits (09). Letters and numbers can be repeated. The number of possible passwords equals _____.
A. 26*25*24+10*9*8
B. 26^3+10^3
C. 26^3*10^3
D.26*25*24*10*9*8

Each of the first three characters is 26 choices each (repetition permitted).
Each of the following digits has 10 choices (numbers can be repeated).
Total number of distinct passwords is the product of all these number of choices.