This very useful book is designed as a companion to The Economist's "Style Guide" and is all about solving problems and making decisions using numbers.

Numerical methods described range from the simple, such as how to calculate percentages and interest to the complex methods of how to calculate the merits of competing investment opportunities.

Numerical methods, the book notes, amount to little more than applied logic, they all reduce to step-by-step instructions and can be processed by simple computing devices.

Yet numerical methods are exciting and powerful, which is why there are often shrouded in mystery.

The book tries to explain why as well as how these different methods work with an attempt to provide a simple and intuitive explanation, often with case illustrations.

It also contains a handy glossary of terms and key models covering items from amortisation to zero sum game.

One of the more interesting chapters of the book outlines techniques that aid decision-making and shows how to bring your own judgment into the analysis.