I know this really doesn't matter, but I've noticed that when I use my various cards, there's something distinctive about the authorization codes on a few of them.
Discover It Card - always ends in 'R'
Capital One QS Mastercard - always ends in 'B'
Capital One QS Visa - always ends in 'D'
Synchrony/Sam's Club Mastercard - always ends in 'Z'
USAA Visa - all numeric
Amex Green - all numeric
Amex BCP - all numeric
USAA Debit MC - always ends in 'H'
I know that years ago, most Amex auth codes were two digits, usually in the 20s or 30s (ex. 22, 27, 31, etc.) Back then, it was common to get the same auth code numerous times in the same day using an Amex card, at least it was for me. Now, my Amex cards give a standard six-digit auth codes like many cards use.
Have you noticed anything distinctive about the auth codes on your own transactions? Does anyone know if the letters are significant?
