2:5
4:10
8:20
16:40
Hope that helps:)
In this question, we made a license that does not allow repeated digit and letter. That means the probability count of letter and digit will be decreased by 1 for every roll.
There is 10 kinds of digits (0-9) and 26 kinds of letters (a to z). So, 2 digits and 5 letter would be:
(10 * 9) * (26 * 25 * 24 * 23 * 22)= 710424000 kinds of license plates
