Credit Card numbers

[bhavesh]

Hi,
Does anybody know whether last five digits of a credit card number of a particular type is unique or not.
for eg. last 5 digits of my cc number (Mastercard) is 12345. Is this number unique among mastercard holders?
I am writing a code hence need to know info about CC numbers.
Thanks in advance.
Bhavesh

[Anon]

Does anybody know whether last five digits of a credit card number of a particular type is unique or not. <<

No

[[deleted]]

If those numbers are unique that would mean that there can be 'only' 100000 Master-Card clients.... methinks not.

[csaba]

There is a checksum on credit card numbers, but I have forgotten exactly how it works (it was something like adding up all the digits and then again adding every other one into the sum). It could detect, but not correct an error in one digit.

Csaba

Also, I'm sure you know, MC starts with 5, Visa with 4, and Amex with 3