One of the paid sites wanted to do a credit card check. Since I was reluctant to share this info, i just came up with a number and typed it in. Incidentally, the system recognized that the number was fake even before i pressed the submit button.
Amazed, I checked out to find that the credit cards follow a Luhn Algorithm to preprocess the number before submitting it to the VISA/MaterCard/Amex.

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Comment by dsfddhf hjdjhfjdf — October 16, 2008 @ 10:04 AM