The Rule of 72 Do you know how long it may take for your investments to double in value? The Rule of 72 is a quick way to figure it out. Share | Related Content What Can a Million Dollars Buy You? $1 million in a diversified portfolio could help finance part of your retirement. A Decision Not Made Is Still a Decision Investors who put off important investment decisions may face potential consequence to their future financial security. 5 Smart Investing Principles Principles that can help create a portfolio designed to pursue investment goals.