This book is a brief and handy guide to the use of the BAIIPLUS financial calculator that provides step-by-step instructions for solving financial mathematics problems along with brief explanations of the relevant financial theory related to the selected example types of problems included herein. Thus, it provides not only the how to but also the why of financial mathematics. The value of a dollar today is not the same as the value of a dollar tomorrow or sometime in the future. Thus, the principle of time value equivalence allows us to compare monetary values from different time periods. Business managers first forecast expected cash flows from potential investment projects. Then they discount the cash flows to find their present value. Then they compare this present value to the cost of making the investment. If the net present value is positive (the present value exceeds the cost), they then make the investment. Individuals also forecast the expected dividend cash flows they expect to receive if they buy a common stock of a business firm. They then discount these expected cash flows to find the present value. If the forecasted present value exceeds the current price of the stock, then they buy it. Thus, everyone should be aware of the time value of money.