Albert Einstein put it very simply

By PAUL B. FARRELL.

Albert Einstein put it very simply:

"There is no greater power known to man than compounding interest." Compounding is more powerful than nuclear energy. A 25-year-old can put roughly $3,000 in an IRA every year and with ten percent average returns retire a millionaire at 65. Notice the explosive power: At 65, most of your million dollar retirement portfolio will be in the growth. For example, the 25-year-old will have invested only $120,000 over 40 years; the rest is compounded interest and appreciation!
Albert Einstein is credited with discovering the compound interest rule of 72. Referring to compound interest, Albert Einstein is quoted as saying: "It is the greatest mathematical discovery of all time"

The Rule of 72:
To be able to do compound interest problems in your head, the Rule of 72 gives you a lightning fast benchmark to determine how good (or not so good) a potential investment is likely to be.
The rule of 72 says that in order to find the number of years required to double your money at a given interest rate, you can just divide the interest rate into 72. For example, if you want to know how long it will take to double your money at eight percent interest, divide 8 into 72 and get 9 years.
The rule of 72 is remarkably accurate, as long as the interest rate is less than twenty percent.
You can also run it backwards. If you want to double your money in six years, just divide 6 into 72 to find that it will require an interest rate of about 12 percent.
YES, you will be tested on The Rule of 72 in the future. Study now. :)