A **number** is a term that describes the amount of something and is used for counting of measuring.

Numbers are usually represented in English writing in a Base Ten system of *numerals*:

- 0 (zero)
- 1 (one)
- 2 (two)
- 3 (three)
- 4 (four)
- 5 (five)
- 6 (six)
- 7 (seven)
- 8 (eight)
- 9 (nine)

Which can be used in combination to represent any number of any size. An older system of representation, still sometime encountered on clocks and other places, is Roman numerals, which used certain letters of the alphabet instead.

There are many kinds of numbers. Some examples are:

- Prime numbers
- Composite numbers
- Rational numbers
- Real numbers
- Imaginary numbers
- Complex numbers
- Transcendental numbers

"Number" is also a grammatical term for the representation of a number of persons or things in a form of a word.