**We sometimes need to find out how long it will take a sum of money (or something else, such as earnings, population, or prices) to grow to some specified amount. For example, if a company’s sales are growing at a rate of 20% per year, how long will it take sales to double**?

Solution

To find the number of year we will user NPER function in excel. Since the amount should be double we will used present value of 100 and Future value of 200 in the formula

Rate 20.00% ← Growth Rate

PMT 0 ← 0

PV -100 ← Present value assumed 100

FV 200 ← Future value 2 x 100 = 200

Year 3.801784017 ← Select Cell to see calculation. =NPER(20%,0,-100,200)