Following an email from Alison Eddy asking about tools for calculating the rate of return on investments, I have to say that my systematic analysis usually involves a biro and the back of an envelope or, if I’m feeling particularly slick, a calculator. However, I have been pointed in the direction of this c++ source code for investment calculator which, providing you’re reasonably au fait with doing a bit of simple coding (this really isn’t rocket science) can help you work out rates of return or return on investment (ROI) on your various investments, and get a handle on compound interest. The key thing to bear in mind here is that there are as many ways to calculate rate of return on investment as there are rotten new groups appearing on the X-Factor each year. Different measuring systems will give different returns, as you can work out the return on the total sum invested or just the sum you invested for instance (so if you put £20,000 down on a £200,000 house and it rose £2000 in a year you could calculate it as a 1% absolute return or a 10% return on your investment, for example). Then you have to factor in depreciation, the opportunity cost of what the money could be doing, and so on. Anyway, a place to start. Check out the c++ source code for investment calculator here. Check here to find some guidance on what is compound interest and why it’s so important to your investments.