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Cardinaleighteen
Ordinal18th
(eighteenth)
Numeral systemoctodecimal
Factorization2 \cdot 3^2
Divisors1, 2, 3, 6, 9, 18
Roman numeralXVIII
Binary10010
Octal22
Duodecimal16
Hexadecimal12

18 (eighteen) is the natural number following 17 and preceding 19. 17 ( seventeen) is the Natural number following 16 and preceding 18. 19 ( nineteen) is the Natural number following 18 and preceding 20. In mathematics Nine is a Composite number, its proper Divisors being 1 and 3. 17 ( seventeen) is the Natural number following 16 and preceding 18. 19 ( nineteen) is the Natural number following 18 and preceding 20. "Twenty" redirects here For the village in England, see Twenty Lincolnshire. This is a list of articles about Numbers ( not about Numerals. The integers (from the Latin integer, literally "untouched" hence "whole" the word entire comes from the same origin but via French "Twenty" redirects here For the village in England, see Twenty Lincolnshire. 30 ( thirty) is the Natural number following 29 and preceding 31. 40 ( forty) is the Natural number following 39 and preceding 41. This article discusses the number fifty. For the year 50 CE see 50. 60 ( sixty) is the Natural number following 59 and preceding 61. 70 ( seventy) is the Natural number following 69 and preceding 71. 80 ( eighty) is the Natural number following 79 and preceding 81. 90 ( ninety) is the Natural number preceded by 89 and followed by 91. This article describes cardinal numbers in mathematics For cardinals in linguistics see Names of numbers in English. In linguistics ordinal numbers are the words representing the rank of a number with respect to some order in particular order or position (i A numeral system (or system of numeration) is a Mathematical notation for representing numbers of a given set by symbols in a consistent manner In Mathematics, factorization ( also factorisation in British English) or factoring is the decomposition of an object (for In Mathematics, a divisor of an Integer n, also called a factor of n, is an integer which evenly divides n without Roman numerals are a Numeral system originating in ancient Rome, adapted from Etruscan numerals. The binary numeral system, or base-2 number system, is a Numeral system that represents numeric values using two symbols usually 0 and 1. The octal Numeral system, or oct for short is the base -8 number system and uses the digits 0 to 7 The duodecimal system (also known as base -12 or dozenal) is a Numeral system using twelve as its base. In Mathematics and Computer science, hexadecimal (also base -, hexa, or hex) is a Numeral system with a In Mathematics, a natural number (also called counting number) can mean either an element of the set (the positive Integers or an 17 ( seventeen) is the Natural number following 16 and preceding 18. 19 ( nineteen) is the Natural number following 18 and preceding 20.

Contents

In mathematics

Eighteen is a composite number, its proper divisors being 1, 2, 3, 6 and 9. A composite number is a positive Integer which has a positive Divisor other than one or itself In Mathematics, a divisor of an Integer n, also called a factor of n, is an integer which evenly divides n without Mathematics For any number x: x ·1 = 1· x = x (1 is the multiplicative identity In mathematics Two has many properties in Mathematics. An Integer is called Even if it is divisible by 2 ---- In mathematics Three is the first odd Prime number, and the second smallest prime In mathematics Six is the second smallest Composite number, its proper Divisors being 1, 2 and 3. In mathematics Nine is a Composite number, its proper Divisors being 1 and 3. Three of these divisors (3, 6 and 9) add up to 18, hence 18 is a semiperfect number. In Mathematics, a semiperfect number or pseudoperfect number is a Natural number n that is equal to the sum of all or some of its Proper

It is a heptagonal number, and as the sum of the first three pentagonal numbers, it is a pentagonal pyramidal number. A heptagonal number is a Figurate number that represents a Heptagon. A pentagonal number is a Figurate number that extends the concept of triangular and Square numbers to the Pentagon, but unlike the first A pentagonal pyramidal number is a Figurate number that represents the number of objects in a pyramid with a Pentagonal base It is also the sum of the totient function for the first seven integers. In Number theory, the totient \varphi(n of a Positive integer n is defined to be the number of positive integers less than or equal to

The aliquot sum of 18 is 21 and its aliquot sequence is (18,21,11,1,0). In Mathematics, and specifically in Number theory, a divisor function is an Arithmetical function related to the Divisors of an Integer In Mathematics, an aliquot sequence is a recursive sequence in which each term is the sum of the Proper divisors of the previous term

In base 10 it is a Harshad number. A Harshad number, or Niven number, is an Integer that is divisible by the sum of its digits in a given number base.

18, aside from 0, is the only number that equals twice the sum of its decimal digits.

In science

In religion and literature

As lucky or unlucky number

Age 18

In many parts of the world, 18 is the age minimum for purchasing tobacco and alcoholic beverages. Tobacco is an Agricultural product recognized as an addictive drug processed from the fresh Leaves of plants in the genus Nicotiana. It is also the voting age in many countries. During the Vietnam War, Americans could be drafted at an age as low as 18, but were not allowed to vote in most states until they were 21. The Vietnam War, also known as the Second Indochina War, or the Vietnam Conflict, occurred in Vietnam, Laos and Cambodia A movement spread to lower the voting age, and in 1971, the Twenty-sixth Amendment extended a guarantee of suffrage to anyone 18 years or older in all states. Year 1971 ( MCMLXXI) was a Common year starting on Friday (link will display full calendar of the 1971 Gregorian calendar. The voting age was lowered from 21 to 18 in the U.K. and many other nations around that time. The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located

Eighteen is also the age in many countries at which a person may appear in a pornographic video, or express legal consent to sexual relations with another. Consent as a term of jurisprudence is a possible defence (an Excuse or justification against civil or criminal liability

In addition, eighteen year-olds in the United States have the right to bear arms, own property, marry without parental consent, get an abortion, donate their body to science, and serve on a jury. With these new privileges come responsibility: eighteen year-olds are tried as adults in court.

In the United Kingdom, eighteen-year-olds can purchase tobacco, alcohol, pornography, go to war, vote, and model for pornography; (but the age of consent is 16). The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located Tobacco is an Agricultural product recognized as an addictive drug processed from the fresh Leaves of plants in the genus Nicotiana. In Chemistry, an alcohol is any Organic compound in which a Hydroxyl group ( - O[[hydrogen H]]) is bound to a Carbon Pornography or porn is the explicit depiction of Sexual subject matter with the sole intention of sexually exciting the viewer War is an international relations Dispute, characterized by organized Violence between National Military units Pornography or porn is the explicit depiction of Sexual subject matter with the sole intention of sexually exciting the viewer

In many countries 18 is the age of majority. The age of majority is the threshold of Adulthood as it is conceptualized (and recognized or declared in Law.

In many states in which one can obtain a learner's permit without parental consent.

Minimum age at which one can be admitted to, rent, or buy an MPAA rated NC-17 movie. The Motion Picture Association of America's film-rating system is used in the U This is also the age at which one can see an NC-17 rated movie. The Motion Picture Association of America's film-rating system is used in the U

Minimum age at one can play, rent, or buy an ESRB rated AO game. The Entertainment Software Rating Board ( ESRB) is a self-regulatory organization that applies and enforces ratings, Advertising guidelines and

Minimum age at which one can rent, buy, or buy tickets to an 18A rated film in Canada without being accompanied by an adult. Ratings in Canada are provincal, so they may vary. A film can be 18A in some provinces and 14A in other province. A film can also be 18A in some provinces and R in other provinces. 18 is also the minimum age at which one can view, rent, or buy an R or an A rated movie.

Minimum age at which one can buy, rent, view, or buy tickets to an 18+ rated movie in the Canadian province of Quebec.

Minimum legal age to drink and/or buy alcohol in many countries in the world.

Minimum age at which one can get a full driver's license in many U. S state and Canadian provinces.

Minimum age to drive a car in many countries in the world. See also: 18 certificate, Coming of age

Minimum age in which one can enter a pub or a club in the UK. The 18 certificate is issued by the British Board of Film Classification (BBFC to state that in its opinion a film or video recording should not be seen or purchased Coming of age is a young person's transition from Adolescence to Adulthood The age at which this transition takes place varies in society as does the nature

Minimum age at wich you can legally buy marijuana in the Netherlands. Cannabis, also known as marijuana or marihuana, or ganja (from Hindi / Sanskrit: गांजा gānjā hemp) is a

In other fields

Eighteen is also:

Historical years

A.D. 18, 18 B.C., 1918, 2018, etc. Year 18 was a Common year starting on Saturday (link will display the full calendar of the Julian calendar. Year 18 BC was a Common year starting on Thursday (link will display the full calendar of the Julian calendar. Year 1918 ( MCMXVIII) was a Common year starting on Tuesday (link will display the full calendar of the Gregorian calendar (or a Common 2018 ( MMXVIII) will be a Common year starting on Monday of the Gregorian calendar.

See also

Notes

  1. ^ N James. A numeral system (or system of numeration) is a Mathematical notation for representing numbers of a given set by symbols in a consistent manner The Early Composition History of Catch-22. In Biographies of Books: The Compositional Histories of Notable American Writings, J Barbour, T Quirk (edi. ) pp. 262-90. Columbia: University of Missouri Press, 1996
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