# Number

A number can be thought of as a concept or an idea that indicates how many or how much. There are many different classifications or categories of numbers. Feel free to explore the rest of the site to learn more about various types of numbers. Below are a few examples and a basic definition of numbers.

The number of each set of objects pictured below can be named by the numeral 3:

A number may be named in more than one way: with words, in standard form, and in expanded form.

Example

Word form | : | two hundred thirty-four |

Standard form | : | 234 |

Expanded form | : | 200 + 30 + 4 |

### Did you know?

The concept of number is so abstract that a general mathematical definition has not been written for this term. Mathematicians worked for many, many years to find the words to define number accurately. Finally, they decided that the best way was to use a specific example. Although many people use the word number to mean numeral, they are not the same. Numerals are used to represent numbers, and one number can be represented with many different numerals. For example, some of the ways to represent three are 3, III (Roman numerals), and 2 + 1.

See also approximate number, cardinal numbers, compatible numbers, composite number, counting numbers, decimal mixed number, even number, expanded form, figurate number, fractional numbers, integer, irrational numbers, mixed number, numeral, odd numbers, ordinal numbers, pentagonal number, perfect number, prime number, rational numbers, rectangular number, square number, standard form, triangular number, whole number, word form.