本文对名义报酬率不同情形下投资回收期的计算进行说明。设:投资现值为P,每一年末年金偿付为A,投资报酬率为i,每年计息一次,投资回收期内年平均通货膨胀率预测值为g(g<0为通货紧缩)。则投资回收期N粗略地可依下式测算: This paper describes the calculation of payback period under different circumstances of nominal rate of return. Suppose the present value of the investment is P, the annual payment of the annual payment is A, the return on investment is i, and the interest is counted once a year. The predicted annual average inflation rate during the payback period is g (g <0 is deflation). The payback period N can be roughly estimated as follows: