## Description

We can’t live without numbers. We encounter them every hour of every day. Numbers have shaped the way we think about the world. They penetrate every aspect of our life. Our whole society is organized with the help of numbers; it depends on numbers in many respects, and it has been that way since the dawn of civilization. Numbers rule our life.

We need numbers for counting, for measuring, and for doing calculations. We have numbers to describe dates and times and to tell the price of goods and services. We use numbers when we buy our meals or count our days. Numbers can be manipulated to improve statistics or to cheat in games. We are identified by Social Security numbers, license numbers, credit card numbers, and telephone numbers. Numbers describe sports records, baseball scores, and batting averages. Science, economy, and business are all about numbers, and we find numbers even in music, for example, in rhythm and harmony. To some, numbers are a never-ending source of joy and fascination, while others feel that numbers are depressing, impersonal, often incomprehensible, and without soul. Undoubtedly, people who lack fundamental skills with numbers will face diminished life chances, difficulties finding a job, and other serious impairments in everyday life, similar to people who can’t read.

The immense importance of numbers should make us pause a bit and think about their nature and their origin. What are numbers? Where do they come from? Who was the first to use them? Indeed, there is more to these questions than meets the eye. In order to find answers, we will embark on a journey that visits the realms of psychology, ethnology, history, and philosophy. In the course of this journey, we will learn about ourselves, our mind, and our number sense; we will think about reality and mathematics; and we will encounter fascinating ideas and surprising facts.

Indeed, what is a number? At first, this may seem like a rather odd and unnecessary question. The symbols 1, 2, 3, 4, and so on appear so utterly familiar; their meanings seem so obvious that an explanation can only create confusion. Numbers belong to our shared knowledge about the world. We all recognize a number when we see one. It is notoriously difficult to explain something that everybody knows already, in particular if one hasn’t thought of it before.

Marvin Minsky, in his book *The Society of Mind*, also muses about the nature of numbers and asks why it would be so difficult to explain meaning to others: “Because what something ‘means’ depends on every different person’s state of mind.”1 The hope that through an explanation or precise definition, “different people could understand things in exactly the same ways” cannot be fulfilled, “because in order for two minds to agree perfectly, at every level of detail, they’d have to be identical.” Nevertheless, “the closest we can come to agreeing on meanings is in mathematics, when we talk of things like ‘Three’ and ‘Five.’ But even something as impersonal as ‘Five’ never stands isolated in a person’s mind but becomes part of a huge network.”

In everyday life, there are many occasions contributing to the growth of the mental network of knowledge and meaning that is associated with a number. Numbers are often encountered in situations that have little to do with mathematics. Think for a moment of a number like four, and you will certainly come up with a lot of situations where this number plays a role (such as, the *four* wheels of a car, the *four* wisdom teeth, the *four* seasons, and so on). Even a less obvious example, like the number nine, produces a lot of associations in various contexts—there are Dante’s *nine* circles of hell, Tolkien’s *nine* rings of power, and the *nine* worlds of Yggdrasil in Norse mythology. Beethoven composed *nine* symphonies; a Chinese dragon has *nine* forms; Europeans like *nine*-pin bowling games; in the Caribbean Sea we find *nine*-armed sea stars; in Jewish culture, the Chanukah menorah is a *nine*-branched candelabrum; a baseball team has *nine* players on the field, and a complete game has *nine* innings. An old saying goes that a cat has *nine* lives; another, that *nine* tailors make a man; and when we are very happy, we are on cloud *nine*. Ramadan is the *ninth* month in the Islamic calendar; normal office hours start at *nine* in the morning; human pregnancy usually lasts *nine* months. Dressing nicely is often referred to as being dressed to the *nines*. Nine is a good number in Chinese mythology, but an unlucky number in Japanese culture, where its pronunciation reminds one of the word for agony or pain. And when we take the whole lot, we take the whole *nine* yards.

**Content**

Acknowledgments

Chapter 1: Numbers and Counting

Chapter 2: Numbers and Psychology

Chapter 3: Numbers in History

Chapter 4: Discovering Properties of Numbers

Chapter 5: Counting for Poets

Chapter 6: Number Explorations

Chapter 7: Placement of Numbers

Chapter 8: Special Numbers

Chapter 9: Number Relationships

Chapter 10: Numbers and Proportions

Chapter 11: Numbers and Philosophy

Appendix: Tables

Notes

Index