I got an Apple Card and I mistakenly scratched the last thre code

You will need to contact Apple Support directly to get help with the missing digits for the card.

If you can't redeem your Apple Gift Card or App Store & iTunes Gift Card - Apple Support

click here ➜ Contact Apple Support.

You might need to provide:

• An image of the front and back of your card in full.
• A sales receipt showing when your card was purchased.
• The serial number on your card. 

Do not post this info here in the forums. The Apple Support person will provide a way to send them the information.

Do you have the receipt that should have the activation code on it as well