Whenever a user adds a payment card to ApplePay, that combination of card and device is given a unique Device Account Number. Using this number instead of the actual card number forms part of ApplePay's built-in security measures that help to protect a user's data during payment transactions.

One can find this information in the Wallet application in their card details:

  1. Open the Wallet app and tap Apple Card.
  2. Tap the card number icon, then authenticate with Face ID, Touch ID, or your passcode. 
  3. If you don't see the card number icon, you need to update to the latest version of iOS.
  4. You can see your virtual card number next to the Card Number.
  5. To see the last four digits of your card number or Apple Pay card number, tap Additional Card Numbers.

Also, the Device Account Number can be found in the transaction details.