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 From Boats to Brokers From the Dutch East India Company to Wall Street, the stock market has a long and storied history. Four Really Good Reasons to Invest There are four very good reasons to start investing. Do you know what they are? 5 Smart Investing Strategies Getting what you want out of your money may require the right game plan.