Answer:
Use a debit card, or use a credit card and pay the balance in full when the bill arrives.
Step-by-step explanation:
When you use a debit, the amount of the purchase is directly debited from your checking account, so you don't have to pay any interest. But you can also use a credit card to pay for goods. If you pay your balance in full every single month before the grace period ends, you will not pay any interests.