Are compounded growth rates additive or do you need to compound existing compounded growth rates?

No cmpounded growth rates are not additive. You need not compound your problems by compounding compounded growth rates. You have to work ou afresh. If 100 becomes 121, the componded growth rate is 10% for 2 years. If thereafter, 121 grows to 484 in the next two years, the compound growth rate for the second 2 years is 100%. Now, if you want to find the compound growth rate for the entire 4 yeears, you have to work out afresh from the standatd formula with initial value of 100, terminal value of 484 and the period of years as 4. Please calculate. It will be less than 50% but more than 40% compound growth rate for the 4 year period. Take care.