2. The Wyoming license plates consist of a maximum of 7 digits. The first NUMBER correspond to the district from which the license plate came from, there are only 23 districts. Then there is a bucking horse to separate the district from the registration. The registration number must consist of 5 single DIGITS. How many plates are available to the state under these present conditions; (Hint treat the district as a single character)

a. If repetition of digits is allowed on the registration number?

b. If repetition of digits is not allowed on the registration number?