This book is an introduction to the mathematics of finance. Part I focuses on analysis of deterministic cash flows, such as those generated by risk-free instruments such as bonds and annuities. Part II analyzes risky securities, such as stocks and options. This book is suitable for undergraduates in mathematics, economics and business programmes. It contains examples and exercises throughout. The book uses investing as a vehicle to introduce ideas, techniques and applications that might not be encountered in other mathematics courses. These include proofs by induction, recurrence relations, inequalities (in particular, the Arithmetic-Geometric Mean inequality and the Cauchy-Schwarz inequality), and the elements of probability and statistics. The book introduces the reader to principles of investing that will be of life-long practical use. This book targets students at the sophomore/junior level, without assuming a background or any experience in investing.