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. The Great Debate Continues: Active vs. Passive In investments, one great debate asks the question, “Active or Passive Investing: Which Is Better?” Keys to Investing for Retirement There are some key concepts to understand when investing for retirement.