Credit card is 5000 yuan, and the minimum repayment amount is 500 yuan. It takes a total of n days from swiping the card to repayment, and the interest generated during repayment is 0.05% of 5,000 yuan per day, that is, 2.50 yuan per day, totaling 2.5n. After that, the interest is calculated from the first repayment, according to 4500+2.5N In fact, if repayment is stressful, you can apply to the bank for installment payment. The service fee rate of general 12 installment is 0.6% per installment, and the total service fee of 12 installment is 7.2%. 5000 yuan a year, the total service fee is 360, and the monthly repayment is 4 16.66+30, and it needs 5360 yuan to be paid off after one year. According to the minimum repayment amount, if only 10% is paid each time, and N=50 (the number of days from the date of credit card swiping to the first repayment), the first due repayment date is 500, and the unpaid part is 4500+125 (the interest of n days); Repay 465 according to 4625 after one month, and the outstanding balance is 4160+69.3 (interest generated since 4625 for one month); After six months, there is still 3239.9 yuan (including interest) outstanding, and the first five cumulative repayments are 2 129. At this moment, if the total repayment amount is 5368.9, the time is only 200 days.