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 The Real Cost of a Vacation Home What if instead of buying that vacation home, you invested the money? The Anatomy of an Index The S&P 500 represents a large portion of the value of the U.S. equity market, it may be worth understanding. Keys to Investing for Retirement There are some key concepts to understand when investing for retirement.