The interest for the 8,000 installment of the Agricultural Bank of China credit card is calculated as follows:

1. First, take 8,000 yuan as the loan principal.

2. Next, the bank will determine the interest rate of the loan based on the credit rating of the credit card. This interest rate is usually fixed, such as 10 per year.

3. The interest calculation period is determined by bank policies. Common periods include monthly, quarterly or yearly.

4. At the end of each calculation period, interest is calculated based on the loan balance and interest rate, and is added to the loan balance.

5. If there is still an outstanding portion of the loan balance at the end of the calculation period, the interest for the next calculation period will be calculated based on the new loan balance.

6. This cycle continues until the loan is fully repaid.

Summary: The interest calculation for the 8,000 installment of the Agricultural Bank of China Credit Card is based on the loan principal, interest rate and calculation period. It is calculated on a monthly, quarterly or annual basis. The interest will be accumulated based on the outstanding loan balance.

Extended information: The specific details of interest calculation will vary according to the bank's policy. In addition to interest rates and calculation cycles, some banks may also charge other fees, such as handling fees, management fees, etc. In addition, if the customer fails to repay the loan on time within the repayment period, the bank may impose penalty interest on the overdue payment. Therefore, when shopping for installments, customers should understand the relevant interest calculation and repayment regulations.

According to the information provided in the question, we do not know the credit rating, interest rate and calculation period of the credit card, so we cannot give a specific interest amount. The above is a description and explanation based on the general credit card installment payment methods. If you need to know the specific interest amount, please consult the credit card personnel of Agricultural Bank of China. They will provide you with detailed information based on your specific situation.