Hidden in the world of personal finance is the "rule of 72," a simple formula to estimate the time for money to double through compounding interest. Just divide 72 by your investment's annual interest rate. If you get 8%, your money doubles every 9 years. It's a quick mental check on the power of growth and the importance of starting early. What's a financial insight that's been a game-changer for you? Share your wisdom and let's uncover more secrets of smart money management together!