0.6 percent. Upon inquiry, ABC knows that the installment interest rate of ABC's credit card is 0.6%, and the installment repayment of ABC's credit card has no interest, only the installment fee. The installment fee rate of the bank's credit cards is 0.6% per installment, 1 installment is 1 month. The repayment amount of the cardholder in installments is 1000, divided into six installments, and the total cost is 1000.