1, average capital method (diminishing method) * * * repayment interest calculation formula: total interest = principal * monthly interest rate * (loan months /2+0.5), and substitute the data into the formula: 600000 * (5.85 ‰) * (300/2+0.5) = 528255. (Note: The interest rate is monthly, which should be 5.85‰ and 5.85 ‰ (5.85/ 1000).

2. Matching principal and interest method * * * The calculation of repayment interest is divided into two steps: first calculate the monthly repayment amount, and then calculate the total interest:

A, monthly repayment amount = principal * monthly interest rate *( 1+ monthly interest rate) n/[( 1+ monthly interest rate) n- 1]

Where: monthly interest rate = annual interest rate/12, n represents the number of loan months, and n represents the power of n, for example, 300 represents the power of 300 (loan for 25 years and 300 months). Note: When calculating (1+ monthly interest rate) n- 1, you must first calculate what is in brackets, and then multiply and subtract 1.

Substitute data into the formula:

600000*(5.85/ 1000)*( 1+5.85/ 1000)^300/[( 1+5.85/ 1000)^300- 1] =4248.333402

=4248.33 yuan.

B. Total interest = monthly repayment amount * number of installments-principal, and substitute the data into the formula:

4248.333402 * 300-600000 = 674500.0206 = 674500.02 yuan.

3. Matching principal and interest method and average capital method, the principal in the first month of repayment is the same (600,000 yuan), so the interest in the first month is the same, and the calculation formula is: principal * monthly interest rate:

600,000 * (5.85/1000) = 3510 yuan.