(NEW YORK) -- Borrowing money can be very expensive, and most personal finance experts agree that the number-one rule when using credit cards is to pay off the balance in full each month.
"If you don't have that money to pay off the balance at the end of the month you're going to carry that balance, you're going to continue to pay extra in terms of the interest on that balance," says Robert Long, managing editor of Kiplinger.com. "It really is one of the worst debts you can have."
If you don't pay your bill in full, the interest you will have to pay can be over 20 percent. But if you do pay your bill in full, using a credit card may be a money saver.
"That can be an interest free loan on purchases you make for a month. I know lots of people who really prosper from the rewards they get from their credit cards," Long says.
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