The weighted average interest rate of the loan = the sum of the interest actually incurred in the current period of the loan/the weighted average value of the loan principal × 100% The numerator of the above formula "the sum of the interest actually incurred in the current period of the loan" refers to the amount of interest actually incurred in the current period of the loan. The denominator of the above formula "weighted average of loan principal" refers to the weighted average of loan principal balance during the accounting period, and its calculation should be determined according to the ratio of the principal of each loan multiplied by the actual number of days occupied by the current loan and the number of days covered by the accounting period. The calculation formula is: weighted average of loan principal = ∑ (each loan principal × the number of days actually occupied by each loan/the number of days covered in the accounting period). To simplify the calculation, the number of months can also be used as the weight for calculating the weighted average of loan principal.