if you pay in full before the final repayment date, you can enjoy the interest-free period. If you only pay the minimum repayment amount, your personal credit will not be affected, but the consumption will not enjoy the interest-free period, and the bank will charge interest at the rate of five ten thousandths of a day from the date when your consumption is credited.

suppose you spend 31 yuan, and the interest for 3 days is almost 31*.5*3=46.5. This is my approximate estimate, and you should take it as shown in the next bill.