1. (3 pt.) License plate numbers in a certain state consist of seven characters. The rst character is a digit (0-9), the next four characters are capital letters (A-Z), and the last two characters are digits (0-9). How many different license plate numbers are possible if... a. (1 pt.) digits and letters can appear more than once? b. (1 pt.) no digit appears more than once? c. (1 pt.) no digit or letter appears more than once