I have a gift card for a gas station and I can't remember how much is left on the card because I have 2 different receipts and I had 2 different gift cards for this gas station. And I don't want to go to this gas station and figure out that I don't have any money left on it because I don't have any cash. Can I call the gas station and give them the number on the card so they can tell me the amount left? Or do they have to scan it?