First, calculate the loan interest rate.

Formula loan amount = monthly repayment amount *[ 1-( 1+ monthly interest rate)-repayment months]/monthly interest rate.

70000 =1300 * [1-(1+monthly interest rate) -60]/ monthly interest rate

Monthly interest rate =0.36 186%

Annual interest rate =4.34237%

Second, calculate the remaining principal after the 12 period.

The formula residual principal = monthly repayment amount *[ 1-( 1+ monthly interest rate)-(remaining months-1)]/ monthly interest rate.

Residual principal =1300 * [1-(1+0.36186%)-47]/0.36186%.

Residual principal = 56,093.57 yuan

Three. Calculate the one-time repayment amount after 12 installment.

Formula lump-sum repayment amount = {loan amount-monthly repayment amount *[ 1-( 1+ monthly interest rate)-months paid]/monthly interest rate} * (months paid+1)

Lump-sum repayment amount = {70000-1300 * [1-(1.36186%)-12]/0.36186%}

One-time repayment amount = 57,393.57 yuan

Results:

The remaining principal after 12 period is 56,093.57 yuan; After 12 installment, the loan can be paid off by one-time repayment of 57,393.57 yuan.

Paying off the loan in advance can save interest of 5006.43 yuan.