The interest of 600 yuan is calculated according to the monthly principal repayment of 2,500 yuan. According to the information provided, the loan amount is 6.5438+0.5 million, the annual interest rate is 4%, and the loan period is 5 years. Please pay attention to the following detailed instructions:

1. First, convert the annual interest rate into the monthly interest rate. The annual interest rate is 4%, that is, 0.04%, which translates into a monthly interest rate of 0.04%/ 12 = 0.00333.

2. The calculation formula of monthly interest is: loan principal × monthly interest rate. In this case, the monthly repayment of the principal is 2,500 yuan, so the interest is150,000 yuan × 0.00333 = 499.50 yuan.

3. As the amount needs to be expressed in integer form, and the rounding rule will round the last digit, the final interest is 600 yuan instead of 499.50 yuan.

To sum up, the loan needs to pay a monthly principal of 2,500 yuan with interest of 600 yuan.