With a 13% annual return, an investment can double in approximately 5.5 years, and multiply by 16 times in 20 years due to compounding.
"So if you are earning 12 13%, let's take 13, then 72/13 is approximately 5 to 6 5 1/2, so your money doubles in 5 1/2 years, which means you can multiply your money by about 16 times in a period of 20 years."