Note that when calculating the interest for one year, it is always divided by 2, but when calculating the principal, it is never divided by 2, because it is assumed that the loan is obtained in the middle of the year, so only the interest for half a year needs to be calculated.

If the loan is made at the beginning of the year, the interest amount should be calculated on an annual basis. If the loan is made at the end of the year, the interest amount will be zero and included in the next year. If the loan is made on June 30th in the middle of the year, the interest is calculated as half a year, so it is divided by 2.