This book provides a text suitable for an introductory course in the mathematics related to computing, generally referred to as discrete mathematics. The increasing number of texts in this area tend to presuppose mathematical sophistication and adopt a highly formalized style. The authors of this book aim to provide a "user-friendly" approach, relying on heuristic justification of results rather than formal proofs. In this respect the book should suit the needs of HND and HNC students in the UK, and those of computer scientists with little mathematical background in both the UK and the US. Topics covered include set theory, logic and methods of proof, graphs, diagraphs and tress, number systems and matrix algebra and an introduction to binary codes. Throughout the book, the interrelations between the mathematical structures and their representatives is stressed, and use is made of "action diagrams" as a language-independent means of presenting algorithmic processes.