**0.1: What is math, exactly?**

Of all the subjects taught in schools throughout the world, mathematics is possibly the one which has collected the image of being most feared and disliked.

So, to start, what is math? What makes it so different from other areas of study, like languages or history? And more importantly, why on Earth do you need to know anything about it?

## Definition

editMathematics is such a wide and broad field of study. To define it would be very hard.

### Study of patterns

editMathematics is a study of patterns—finding patterns and explaining why such patterns exist. Patterns are everywhere: shapes (What is the area of this? What is the volume of that?), counting (How many ways are there to do this? How many are there of that?), and more.

One particularly interesting class of patterns is the patterns of numbers. Whole numbers, for example, look simple but they're not: 1, 2, 3... everyone knows what they are, everyone is familiar with their addition and multiplication. But there are subtle and profound patterns lurking. For example, we can look at what numbers are formed when we repeatedly add 2. 2, 4, 6, 8... We can look at what numbers are formed when we repeatedly add 3: 3, 6, 9, 12... It's easy to see that every number falls into at least one of these sequences, but how many does it fall into, and which ones? For example, 12 is in the sequence 2, 4, 6, 8, 10, 12...; 3, 6, 9, 12...; 4, 8, 12...; 6, 12...; and 12... What numbers fall into only one sequence? These numbers get a special name, prime numbers, because they are only divisible by one and themselves. Finding prime numbers is an extremely tricky question and forms the mechanism for protecting your privacy on the internet. The first few prime numbers are 2, 3, 5, 7, 11, 13, 17, 19, 23 and 29. How many of them are there? 3 and 5 are 2 apart, so are 5 and 7, and 11 and 13, and 17 and 19. How many pairs are there like this?

There are all sorts of questions to ask about these simple sequences, and some of them lead to very profound statements about the structure of numbers.

But why are there such patterns? Why is it that there *has* to be an infinite number of primes? It's possible to imagine that this stream of numbers just stops, maybe after billions and billions of primes, maybe there are so many that people will never be able to compute them all—but why is that impossible? Why is it that if you imagine that, then, if you are very imaginative, you will see that it is absurd?

The asking of questions about pure patterns is mathematics, as well as answering why it must be that way.

### Art of making conjectures and theorems

editMathematics is an art of making conjectures and theorems—guesses about patterns. It is about explaining patterns like primes (How many are there?). There are so many conjectures and theorems, especially in geometry.

Conjectures and theorems are important in math. They say what can be done and what cannot. These things are discoveries, made by people who looked at patterns and found rules about them. For example, the numbers formed when we multiply by 2 are called the even numbers. There are special rules about them. For example, if you add any two even numbers together, you get another even number. That is what is called a theorem. It is a discovery about a pattern.

### Study of logic

editMathematics is a study of logic—proving the conjectures. It is about showing why the conjectures and theorems are true.

This is important in geometry. In fact, many mathematicians want to prove many things, even up to today. There are many conjectures about patterns that still aren't proven.

### Conclusion

editNow, why would you want to know about it? Simple. Because it is fun and because it is interesting.

## Understanding Our World

editTo give an exact definition for a subject as broad as mathematics is not easy. It is not just the study of numbers but taking what we know, realizing patterns and organizing it all into a something that we can work with and understand. Throughout the history of math there have been several ways to organize numbers, the most common way now is the decimal system but even today we still use several others. When man was just a nomad there was no need for numbers, the number of people in clan was small and all you had worry about was food and surviving day to day. As we started to settle down, make camps, towns and eventually cities and empires we needed new ways to talk about numbers. How many sheep are in the flock? How many people live in the tribe? How far is it to the next town? There were all things we needed numbers for to be able to communicate and understand what others were saying. There are countless things that we describe using numbers and quantities to understand their meaning.

## Discovery

editA large part of Mathematics is discovery. After we defined the numbers and how we were going to measure lengths there was math everywhere just waiting to be unveiled. The area of a rectangle has always been the length times the width( ) but until we had numbers to define our length and width it could not be discovered. Volumes, prime numbers and multiples are all parts of mathematics that were just waiting to be discovered. The discoveries now are a lot more complicated to understand but they still exist.

## Invention

editOften math research leads us to a point where we can’t go any further without a little invention. Imaginary numbers, which you will work with later in this book, are one example of where we had to create something to make the math work. Imaginary numbers in the real world do not exist but they have to exist to explain some of the things that happen in our physical world. We invented them to make math work in a manner that could explain the patterns we could observe.

## Abstract

editMathematics is where we find some our first abstract thoughts. A number is not the same as a letter; letters each make a noise and when we put them together they make a word that represents a noun or verb or some other part of speech. Every number represents a different quantity and even more confusing is that two 3s do not make 6 but 33. It is easy to see that 3 fingers on your left hand and 4 fingers on your right come together to make 7 and that is why you will often see grade school students adding in this fashion. Even as we become more accustomed to adding, the simple facts, like adding the numbers between 1 and 9, are often memorized instead of picturing 5 of something and 8 more of them in our mind we memorize that 8 + 5 = 13. To convince you just little bit more that numbers are abstract define the letter B using only words in the definition. Now try to define the number 6 without using numbers.