Matching principal and interest method: loan principal: 170000, assuming annual interest rate: 4.900%, loan term: 20 years, monthly repayment amount of principal and interest:112.55 yuan, and total repayment amount of principal and interest: 2670/kloc-0. The interest paid in 1 month is: 694.438+07; The first 1 month principal repayment is: 418.38; Since then, the monthly interest repayment amount has decreased and the principal has increased. (without considering the adjustment of interest rate in the middle)