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 Bursting the Bubble Tulips were the first, but they won’t be the last. What forms a “bubble” and what causes them to burst? Global vs. International: What’s The Difference? International funds invest in non-U.S. markets, while global funds may invest in U.S. stocks alongside non-U.S. stocks. Keys to Investing for Retirement There are some key concepts to understand when investing for retirement.