This book is written for owners of a BBC microcomputer or an Electron, who would like to know that little bit more about some mathematical techniques. You probably know what program you want to write but maybe you are not quite sure of the mathematics needed. Is it COS, ABS, or SGN that you need? All the mathematical functions that you find on the BBC/Electron are described and their use is illustrated in short programs. You can lift these programs and utilise them within your own programs. But this book is not just an introduction to these basic mathematical functions. It contains background information and programs on such diverse subjects as codes and cryptography, random numbers, sequences, trigonometry, prime numbers, and statistical data analysis. You can utilise this information in both serious and games programming. *Written by Czes Kosniowski*