My bank has a policy of disallowing certain pin numbers. Pins are the standard 4 digits. Pins that have all the same digit (1111), a sequence of digits forward or reverse (1234, 4321), as well as pins that start with 19 or 20 (1999) are disallowed. A 4 digit pin has 10,000 possible pins minus those disallowed. My questions is how many allowed pin possibilities exist?