Matching principal and interest method: the total loan amount is 680,000 yuan, assuming that the annual interest rate at that time is 4.900% and the loan term is 20 years. The monthly repayment amount of principal and interest is 4,450.22 yuan, the total repayment amount is 65,438+0,068,052.8 yuan, and the * * interest payable is 388,052.8 yuan. (without considering the adjustment of interest rate in the middle)

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The number of months returned is 16 months; * * * interest is 43,590.83, * * principal is 276 12.69, and the remaining principal is 652,387.5438+0.

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The proportion of interest paid to the total interest payable is = 1 1.23%, and the interest paid is not much. It is more economical to repay 654.38 million yuan in advance.