The number 5 is the first digit of all account numbers associated with which major credit card?

The number 5 is the first digit of all account numbers associated with which major credit card?

The correct answer is Mastercard. Every Mastercard credit card number begins with the digit 5. This prefix, known as the Major Industry Identifier (MII), helps identify the network that issued the card. Mastercard uses numbers in the range 51–55 and more recently 2221–2720 for its new Bank Identification Numbers (BINs).

Credit card numbers follow a globally standardized structure defined by the ISO/IEC 7812 standard. The first six digits (known as the Issuer Identification Number) indicate the card network and the issuing bank, while the remaining digits identify the customer’s account and include a final check digit verified by the Luhn algorithm.

Other major credit card networks also have distinct starting digits: Visa cards always begin with 4, American Express cards start with 34 or 37, and Discover cards typically begin with 6. These identifiers ensure smooth transaction routing and fraud prevention across global financial systems.

Mastercard, headquartered in Purchase, New York, is one of the world’s largest payment networks, operating in over 210 countries. The company partners with banks and financial institutions rather than issuing cards directly to consumers. Its branding, symbolized by the iconic interlocking red and yellow circles, has become synonymous with secure digital payments.

Fun fact: Mastercard introduced its first credit card in 1966 under the name “Interbank Card Association.” It officially adopted the name “Mastercard” in 1979 as global usage expanded.