A:AnswerIn Checkout, enter both the card number and 4-digit PIN on the back of the card. If your gift card balance doesn't cover the total cost of your order, we'll charge the remaining amount to your primary form of payment listed in your Best Buy account, or to another acceptable form of payment at your request. If the total cost of the order is less than the balance on your gift card(s), any unused balance will remain on the last gift card you entered.
https://www.bestbuy.com/site/gift-cards/gift-card-faq/pcmcat1526048189330.c?id=pcmcat1526048189330
