HYWD Compounding Calculator
The best way investing work is through compounding your profits over long period of time or having high ROI for a short period of time. Both work best together although this is rarely possible 8-).
With the investment calculator below you can play with different initial investment amount (principal) and various yearly ROIs, additional investments and compounding percentage.
You will notice that the higher percentage of your profits you reinvest, the higher the final amount you have is (which should be rather obvious). Just go ahead and play with some numbers - this may help you figure out an investment strategy.
Don't forget: there are no investments with guaranteed profits. Even bank deposits don't fix your ROI for very long period of time. So don't assume that the figures the calculator gives out will easily become a reality. But use it to build your investment strategies.
To understand better how and why compounding works, check this article at Investopedia.
P.S. If you are looking for investments that can bring you high ROI, have a look at some odd investment ideas.