Dictionary
the property possessed by a sum or total or indefinite quantity of units or individuals "he had a number of chores to do" "the number of parameters is small" "the figure was about a thousand" a concept of quantity involving zero and units "every number has a unique position in the sequence" a short theatrical performance that is part of a longer program "he did his act three times every evening" "she had a catchy little routine" "it was one of the best numbers he ever did" the number is used in calling a particular telephone "he has an unlisted number" a symbol used to represent a number "he learned to write the numerals before he went to school" one of a series published periodically "she found an old issue of the magazine in her dentist's waiting room" a select company of people "I hope to become one of their number before I die" a numeral or string of numerals that is used for identification "she refused to give them her Social Security number" a clothing measurement "a number 13 shoe" the grammatical category for the forms of nouns and pronouns and verbs that are used depending on the number of entities involved (singular or dual or plural) "in English the subject and the verb must agree in number" an item of merchandise offered for sale "she preferred the black nylon number" "this sweater is an all-wool number" add up in number or quantity "The bills amounted to $2,000" "The bill came to $2,000" give numbers to "You should number the pages of the thesis" enumerate "We must number the names of the great mathematicians" put into a group "The academy counts several Nobel Prize winners among its members" determine the number or amount of "Can you count the books on your shelf?" "Count your change" place a limit on the number of
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Wikipedia
: ''This article is about the concept used to describe and assess quantity. For other uses of the term, see Number (disambiguation).''wiktionary A number is an abstract entity used originally to describe quantity. At least since the invention of complex numbers, this definition must be relaxed. Examples - numbers The most familiar numbers are the natural numbers or , used for counting, and denoted by N.If the negative number negative whole numbers are included, one obtains the integers Z.("Whole numbers" are sometimes denoted by W, but it depends on the author if this means positive, non-negative, or all integers.)Rational numberRational numbers are made up of all numbers that can be expressed as a Fraction (mathematics)fraction of integers, though the whole numbers are rational, despite not being fractions, because they can be understood to have been divided by 1. The set of all rational numbers is denoted by Q.The subset of rational numbers having a finite decimaldecimal representation are called decimal fractions or decimal numbers, sometimes denoted by D.The Real numberreal numbers, R, can have an infinite and non-repeating decimal expansion. Real numbers that are not rational are called Irrational numberirrational numbers.The real numbers can be extended to the complex numbers C, which leads to an algebraically closed field in which every polynomial with complex coefficients can be completely factored.The above symbols are often written in blackboard bold, thus::In another respect, roots of polynomials with rational coefficients lead to algebraic numbers, and those complex numbers which are not algebraic are called transcendental numbertranscendental numbers. Iterating the adjunction of imaginary units allows to extendcomplex numbers to quaternions H, losing commutativity of multiplication, and then to octonions, losing associativity and thus leaving the category of associative division algebras.
Further generalizations - Elements of function fields of finite characteristic (algebra)characteristic behave in some ways like numbers and are often regarded as a kind of number by number theorists.
Numerals and numbering - Numbers should be distinguished from ''numerals'', which are (combinations of) symbols used to represent numbers. The notation of numbers as a series of digits is discussed in numeral systems. People like to assign numbers to objects in order to have unique names. There are various numbering schemes for doing so.
Extensions - Superreal numberSuperreal, hyperreal numberhyperreal and surreal numbers extend the real numbers by adding infinitesimal and infinitely large numbers. While (most) real numbers have infinitely long expansions to the right of the decimal point, one can also try to allow for infinitely long expansions to the left in base p, where p is a prime numberprime, leading to the p-adic numbers. For dealing with infinite collections, the natural numbers have been generalized to the ordinal numbers and to the cardinal numbers. The former give the ordering of the collection, the latter its size. (For the finite case, the ordinal and cardinal numbers are equivalent; they diverge in the infinite case.) The arithmetical operations of numbers, such as addition, subtraction, multiplication and division (mathematics)division, are generalized in the branch of mathematics called abstract algebra; one obtains the group (mathematics)groups, ring (algebra)rings and field (mathematics)fields.
See also - Arabic numeral system Even and odd numbers Famous numbers Floating point numbers are used by computers to approximate real numbers Large numbers List of numbers Mathematical constant Mythical number Negative and non-negative numbers Orders of magnitude (numbers) Physical constant Prime number Small number Subitizing and counting Numbers in various languages Number sign Numero sign
External links - !freepages.history.rootsweb.com - Mesopotamian and Germanic numbers
References - Erich Friedman, ''stetson.edu - What's special about this number?'' Alexander Bogomolny, ''cut-the-knot.org - What's a Number?''Category:Group !theoryCategory:Numbers__NOTOC_ _ast:Númberubg:Числоbe: ікbn:সংখ্যাbr:N iverca:Nombrecs:Čísloda:Tald e:Zahlet:Arves:Númeroeo:Nombr oeu:Zenbakifr:Nombregl:Número ko:수? !(수학)hi:अंकhr:Brojid: Angkais:Talait:Numero? !(matematica)he:מספרlt:Skai čiushu:Számnl:Getalja:数no: Tallpl:Liczbapt:Númeroro:Num rru:Числоscn:Nummurusimp le:Numbersl:Številosu:Wilanga nfi:Lukusv:Tal? !(matematik)th:จำนวนt r:Sayızh:数? (数学)
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