# Numbers Index

Numbers are the building blocks of mathematics. A number represents a quantity expressed using symbols.

## Notation

Euler's Number is represented in mathematics with the letter e and has some unique exponential properties.

The greek letter pi is a number in mathematics that describes the ratio a circle's circumference divided by its diamater.

The symbol tau is used in mathematics to represent the ratio of the circumeference of the circle divided by its radius.

Two dimensional space is denoted using the symbol for the set of real numbers followed by a superscript two.

Three dimensional space is denoted using the symbol for the set of real numbers followed by a superscript three.

A complex number is represented in two parts. The first is the real number part and the second is the imaginary number part.

The decimal point is used to separate the whole part of a number from the decimal part. The whole part is represented using number digits to the left of the decimal point. The decimal part is also represented using digits to the right of the decimal point.

Scientific notation is a notation that scientists use to keep track of the number of significant digits in a number as well as easily recognize the magnitude of a number.

The set of complex numbers is denoted using the Latin capital letter C most often presented with a double-struck typeface.

This page explains the notation for the set of integers.

This page explains the notation for the set of natural numbers

This page explains the notation for the set of rational numbers

This page explains the notation for the set of real numbers

## Concepts

Counting is the process of calculating the quantity of a group of objects.

Mathematical constants are symbols that represent useful numbers.

A prime number is a number that is only divisible by itself and one. The set of prime numbers is infinitely big. The first prime numbers are 2, 3, 5, 7, 11, ... and continues on forever.

The set of complex numbers contains all possible complex numbers. Each complex number has a real part and an complex part.

The set of integers is made up of the set of counting integers and each of their negative counter parts.

The set of natural numbers, also called the counting numbers, contains the numbers 0, 1, 2, 3, ...

The set of real numbers contains the set of rational numbers as well as irrational numbers like pi, e, and the square root of two.