The number 5 as the first digit of all account numbers is associated with Mastercard credit cards.

Direct answer

  • The major credit card brand whose account numbers begin with the digit 5 is Mastercard.

Quick scoop explanation

  • Credit card numbers follow an international standard where the first digit identifies the card network. Mastercard is assigned the leading digit 5 in this system.
  • By contrast, Visa numbers start with 4, American Express with 34 or 37, and Discover typically with 6, which is why 5 uniquely points to the Mastercard network among major brands.

So, for the question “the number 5 is the first digit of all account numbers associated with which major credit card?”, the correct answer is: Mastercard.

TL;DR: The digit 5 at the start of a card number indicates a Mastercard.

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