The answer is 16,777,216 combinations.

Explanation:

There is a maximum of 65536 unique card numbers (0 through 65535) with maximum of 256 unique site numbers (0 through 255) possible. To get the answer simply multiply 65536 x 256.

* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
Extra credit question:  Assuming you have all the cards from the question above in your possession, how long would it take to present each cared to a Max 3 System?

Extra credit answer:

The answer is approximately 841 days.

Explanation:

Lets assume it takes 1 second to present each card, the error lockout threshold is set to 3 and the error lockout duration is set to 10 seconds.

1. First divide 16,777,216 by 3 attempts gives you 5,592,405.

2. Multiply 5,592,405 by 13 seconds (One second for each card presentation and 10 seconds for error lockout) and that gives you 72,701,269 seconds.

3. Now divide 72,701,269 seconds by 60 to give you 1,211,687 minutes.

4. Next divide 1,211,687 minutes by 60 to give you 20,194 hours.

5. Finally divide 20,194 hours by 24 to give you 841 days.