CI = cost of investment
GI = gain from investment
n = number of years
For example, we invested 10,000 Euros 5 years ago. The value of the investment today is 30,000 Euros.
We substitute the values into the formula mentioned above.
ROI = (30,000 - 10,000) / 5 = 0.4.
Therefore, the ROI value is 40%, or the annual return is 40%.