Interest rates are generally divided into annual interest rate, monthly interest rate and daily interest rate. The annual interest rate is usually expressed as a percentage. For example, the annual interest rate is 7.2%, which means that the principal is 100 yuan, and the accrued interest for one year is 7.2 yuan. The monthly interest rate is usually expressed in one thousandth. For example, the monthly interest rate is 6‰, which means that the principal is 65,438 yuan+0,000 yuan, and the accrued interest is 6 yuan. The daily interest rate is usually expressed in ten thousand units, for example, the daily interest rate is 20/000, that is, the principal is 10000 yuan, and the daily accrued interest is 2 yuan. In the calculation process, it should be noted that the expression of interest rate should correspond to the expression of deposit term. Year, month and day can be converted into each other, and so can annual interest rate, monthly interest rate and daily interest rate: annual interest rate = monthly interest rate × 12= daily interest rate × 360 month interest rate = annual interest rate ÷ 12= daily interest rate× 30 day interest rate = monthly interest rate ÷30= annual interest rate× 360 month interest rate. The principal can be the deposit amount or the loan amount. Time is the actual time of deposit or loan. Interest rate is the ratio of determined interest amount to deposit amount. The calculation method of interest is divided into simple interest and compound interest. The calculation formula of simple interest is: sum of principal and interest = principal ×( 1+ interest rate× term) interest = principal × interest rate× term. For example, a depositor's five-year time deposit is 1000 yuan, and the annual interest rate is 13.68%. When the deposit expires, the depositor should get interest: 65438+. Compound interest is the symmetry of simple interest, that is, after a certain period of time (such as one year), the accrued interest principal is recalculated and accumulated one by one. The formula of compound interest is: sum of principal and interest = principal (1+ interest rate) n, where n means periodic interest = principal and interest-principal. At present, the calculation method of simple interest is still adopted in China.