Adam Gojdas (8/7/2009)
Closer to being perfect is the LUN 10 checksum (sanity check on credit card numbers)... but even that can have a failure.
Just in case anyone else is interested in finding out more regarding the checksum Jeff mentions I found it is actually:
LUHN10 checksum
Heh... thanks for the correction... I ate garlic and didn't want to breath on anyone too hard so I left the "H" out. 😛
--Jeff Moden
Change is inevitable... Change for the better is not.