What is a Credit Card Account Number?

cred - it card ac - count num - ber
The number that uniquely identifies a specific credit card account.
How Does a Credit Card Account Number Work?

The first 6 digits of the number are the Bank Identification Number, identifying the Issuing Bank. The last digit is a check-digit, used to detect errors. The remaining 9 digits represent the account number assigned to the cardholder. The type of account assigned by the Issuer, for example, classic, debit, signature, business, commercial, and prepaid, is one component in pricing the transaction to the Merchant.

For more information, read "The Payments System Simplified"
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