This book is about number sets, specifically, the kinds of numbers that mathematicians, scientists, and engineers work with daily. Many of the number sets are undoubtedly familiar to you, though you may not use them by their names: the natural numbers, whole numbers, integers, and rationals (fractions). Others are less often used, and some are downright strange but have utility in certain places. Nevertheless, all are worth knowing.

By the end of the book, you’ll know the names, characteristics, and relationships between the major types of numbers. Additionally, you’ll have a good idea of where our number system came from and why it isn’t the least bit special.

Along the way, you’ll learn about sets, operations on sets, and even basic terminology from number theory and abstract algebra. Don’t be concerned if the terms are unfamiliar; they'll be explained to you as you go.

About This Series

The Explainer’s Guides introduce readers to the fundamentals of each topic. No prior knowledge is assumed. The books are written by knowledgeable people and are intended primarily for adults seeking an introduction to the topic. The books are self-contained, and each book concludes by pointing the reader to additional material.