If the mortgage in 2003 was180,000 yuan, you should pay 19 1 1.65 every month. The interest rate is 30% higher than the benchmark. This is the usual equal principal and interest algorithm. At present, there is no such high mortgage interest rate. You should be the average capital.

In this way, the monthly principal repayment =180,000 yuan/(13x12) =1153.85.

Interest paid in the first month =1900-1153.85 = 746.438+05.

If your monthly repayment date coincides with the loan issuance date, the formula is: interest = principal x interest rate x time.

The interest rate = 746.15/180000/30x360 = 4.97436% is 7.6 times of the benchmark interest rate of 6.55%. At present, banks generally don't use this discount, so your monthly repayment date is inconsistent with the loan issuance date, so you should replace 30 in the above formula with the actual number of days, and then you can calculate it yourself.