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This is a list of articles about numbers ( not about numerals ). [ edit ] Rational numbers [ edit ] Natural numbers
1 ( one ; pron.: / ˈ w ʌ n / or UK / ˈ w ɒ n / ) is a number , a numeral , and the name of the glyph representing that number. It represents a single entity, the unit of counting or measurement . For example, a line segment of "unit length" is a line segment of length 1. [ edit ] As a number One, sometimes referred to as unity , is the integer before two and after zero .
2 ( Two ; i / ˈ t uː / ) is a number , numeral , and glyph . It is the natural number following 1 and preceding 3 .
3 ( three ; pron.: / ˈ θ r iː / ) is a number , numeral , and glyph . It is the natural number following 2 and preceding 4 . [ edit ] In mathematics Three is the first odd prime number , [ 1 ] and the second smallest prime. It is both the first Fermat prime (2 2 n + 1) and the first Mersenne prime (2 n − 1), the only number that is both, as well as the first lucky prime . However, it is the second Sophie Germain prime , the second Mersenne prime exponent, the second factorial prime (2!
4 ( four ; / ˈ f ɔər / ) is a number , numeral , and glyph . It is the natural number following 3 and preceding 5 . Four is the only number that has the same number of characters as its value in the English language. [ 1 ] [ edit ] In mathematics Four is the smallest composite number , its proper divisors being 1 and 2 .
5 ( five / ˈ f aɪ v / ) is a number , numeral , and glyph . It is the natural number following 4 and preceding 6 . [ edit ] In mathematics Five is the third prime number .
6 ( six / ˈ s ɪ k s / ) is the natural number following 5 and preceding 7 . The SI prefix for 1000 6 is exa (E), and for its reciprocal atto- (a). [ edit ] In mathematics 6 is the smallest number which is neither a square number nor a prime number . Six is the second smallest composite number ; its proper divisors are 1 , 2 and 3 . Since six equals the sum of its proper divisors, six is the smallest perfect number , Granville number , and
7 ( seven ; / ˈ s ɛ v ə n / ) is the natural number following 6 and preceding 8 . [ edit ] Mathematics Seven, the fourth prime number , is not only a Mersenne prime (since 2 3 − 1 = 7) but also a double Mersenne prime since the exponent, 3, is itself a Mersenne prime.
8 ( eight / ˈ eɪ t / ) is the natural number following 7 and preceding 9 . The SI prefix for 1000 8 is yotta (Y), and for its reciprocal, yocto (y). It is the root word of two other numbers: eighteen (eight and ten) and eighty (eight tens). Linguistically, it is derived from Middle English eighte , and is presumably related to the French huit . [ citation needed ] [ edit ] In mathematics 8 is a composite number , its proper divisors being 1 , 2 , and 4 .
9 ( nine / ˈ n aɪ n / ) is the natural number following 8 and preceding 10 . The ordinal adjective is ninth . [ edit ] Alphabets and codes In the NATO phonetic alphabet , the digit 9 is called "Niner".
10 ( ten i / ˈ t ɛ n / ) is an even natural number following 9 and preceding 11 . Ten is the base of the decimal numeral system , by far the most common system of denoting numbers in both spoken and written language.
11 ( eleven i / ɨ ˈ l ɛ v ɨ n / or / i ˈ l ɛ v ɛ n / ) is the natural number following 10 and preceding 12 . In English, it is the smallest positive integer requiring three syllables and the largest prime number with a single-morpheme name. Its etymology originates from a Germanic compound ainlif meaning "one left". [ 1 ] ). [ edit ] In mathematics 11 is the 5th smallest prime number .
12 ( twelve i / ˈ t w ɛ l v / ) is the natural number following 11 and preceding 13 . The word "twelve" is the largest number with a single- morpheme name in English . Etymology suggests that "twelve" (similar to " eleven ") arises from the Germanic compound twalif "two-leftover", so a literal translation would yield "two remaining [after having ten taken]". [ 1 ] This compound meaning may have been transparent to speakers of Old English , but the modern form "twelve" is quite opaque. Only the remaining tw- hints that twelve and two are related.
A number is a mathematical object used to count , label, and measure . In mathematics , the definition of number has been extended over the years to include such numbers as zero , negative numbers , rational numbers , irrational numbers , and complex numbers . Mathematical operations are certain procedures that take one or more numbers as input and produce a number as output. Unary operations take a single input number and produce a single output number. For example, the successor operation adds one to an integer , thus the successor of 4 is 5.