License Plate 60318 How Many Different License Plate Numbers Can You Have?

How many different license plate numbers can you have? - license plate 60318

. Suppose a set of license plates consist of two letters from a three digit number. How many numbers of plates may be different if
(a) there are restrictions and
(b) The letter O and are not used?
(c) How large is the probability that the selection ends at random a number plate in an even number?