Question

A password must have one letter and two digits. How many different passwords are possible? Hint: 26 letters in the alphabet and 10 possible digits

Answer 1

7020.

Explanation:

The letter could be any 1 of the 26 and it could be placed in any 1 of 3 places so this makes 26*3 = 78 possibilities.

For each of these there is any one of permutations of 2 digits from 10

= 10P2 = 10! / 8! = 10*9 = 90.

So the answer is 78 * 90 = 7020.

Note I am assuming that the 2 digits picked are different - no duplicates.