posted by Carlos .
A license plate is to consist of two letters followed by three digits. How many different license plates are possible if the first letter must be a vowel, and repetition of letters is not permitted, but repetition of digits is permitted?
The first position can be filled in 5 ways, the second place in 25 ways (one of the 26 letters was used in the first spot), followed by each of 10 ways for the third, fourth and fifth positions.
So the number of plates = 5*25*10*10*10
What percent of the first 50 positive integers contain no odd digits?