A PIN (personal identification number) has 4 digits, each of which are 0, 1, ..., 9. Each digit is independent of the others. We select a PIN at random.
(a) What's the probability the PIN is a number greater than the number 1256?
(b) What's the probability all four digits are the same?
(c) What's the probability all four digits are even?
(d) What's the probability the first digit is 3?
(e) What's the probability the first two digits are both 3?