# Calculate real GDP

1. Assume that the annual growth GDP per capita is 2%, how much will the real GDP per capita increase in 10 years. I know the manual way is to take 2 percent every years. For example after 1 year would be (100 x 2 )/100 = 2. So it would be a total of 102. Is there a formula to calculate the percent after 10 years?
2. Let’s say that China’s per capita GDP grow 9% a year for the next 16 years and 6% a year for the next 24 years. What is China’s per capita GDP in 40 years Well this one is kind of the same with the first one, is there a formula to calculate the percentage only. Thank you

A hint for part 2. To obtain an approximate answer, it's convenient to use the rule that the doubling time $D$ in years of a quantity growing exponentially at a constant annual rate $r$ is given approximately by the rule of 72:
$$D = \frac{72}{r}$$