AMEX Card Number Coding
 

Didn't want to get flamed for restarting a 10 yr old thread: https://www.flyertalk.com/forum/amer...rd-number.html

Most AMEX cards begin with 37. The last 4 digits denote the number of times the card has been reissued, the authorized user position, and the check digit.

After the 37, do the next 4 digits still refer to the currency/country code and the product code? They had at one point in time. Is that still the case?

The remaining 5 refer to the account number, but does a particular digit refer to the billing cycle?

This explains why my cards tend to have the same last 4 digits, which causes me a lot of headache when only the last 4 digits are listed on bills, statements, receipts, etc.

I'm surprised the check digit matches across all of them as it's computed based on the other digits. I have 7 and 2 match on the last digit.