In order to obtain the periodic amortization payments ( a_{s} ) of any loan with fractional interest payments you have to work with the effective rate of interest per time unit ( i^{(m)} ), because of that, if you do not enter this rate of interest, it is necessary to do the following conversion: Once calculated the effective rate of interest per time unit ( i^{(m)} ), you have to know that in this kind of operation there is only one principal repayment( A_{m} ) per year, which is in the last amortization payments of each year ( a_{m} ), so the rest of the periodic amortization payments ( a_{1}...a_{m1} ) only pay interest ( I_{s} ). That is why the periodic amortization payments are calculated as follows:
