Because credit card overdrafts are cashed out and compound interest is calculated monthly, it can only be roughly calculated.

1. Withdrawal of principal 500 yuan; Second, the overdraft withdrawal fee is 0.5%, which is the fee of 2.5 yuan;

Third, interest is charged at 0.25 yuan per day, that is, the interest in 0.5 yuan every day is roughly 30 days in 7.5 yuan.

The total repayment amount is about 5 10 yuan.