28 (twenty-eight) is the natural number following 27 and preceding 29. In mathematics, a natural number can mean either an element of the set {1, 2, 3, ...} (i. ... 27 (twenty-seven) is the natural number following 26 and preceding 28. ... 29 (twenty-nine) is the natural number following 28 and preceding 30. ...

← 20 21 22 23 24 25 26 27 28 29 → 19 (nineteen) is the natural number following 18 and preceding 20. ... 20 (twenty) is the natural number following 19 and preceding 21. ... 21 (twenty-one) is the natural number following 20 and preceding 22. ... 22 (twenty-two) is the natural number following 21 and preceding 23. ... This article is about the number 23. ... 24 (twenty-four) is the natural number following 23 and preceding 25. ... 25 (twenty five) is the natural number following 24 and preceding 26. ... 26 (twenty-six) is the natural number following 25 and preceding 27. ... 27 (twenty-seven) is the natural number following 26 and preceding 28. ... 29 (twenty-nine) is the natural number following 28 and preceding 30. ... 30 (thirty) is the natural number following 29 and preceding 31. ... List of numbers — Integers This is a list of articles about numbers (not about numerals). ... The integers are commonly denoted by the above symbol. ... 0 10 20 30 40 50 60 70 80 90 → 0 (zero) is both a number and a numerical digit used to represent that number in numerals. ... 10 (ten) is an even natural number following 9 and preceding 11. ... 20 (twenty) is the natural number following 19 and preceding 21. ... 30 (thirty) is the natural number following 29 and preceding 31. ... 40 (forty) is the natural number following 39 and preceding 41. ... 50 (fifty) is the number following 49 and preceding 51. ... 60 (sixty) is the natural number following 59 and preceding 61. ... Look up seventy in Wiktionary, the free dictionary. ... 80 (eighty) is the natural number following 79 and preceding 81. ... 90 (ninety) is the natural number preceded by 89 and followed by 91. ... 100 (one hundred) (the Roman numeral is C for centum) is the natural number following 99 and preceding 101. ...
Cardinal	28 twenty-eight
Ordinal	28th twenty-eighth
Factorization
Divisors	1, 2, 4, 7, 14, 28
Roman numeral	XXVIII
Binary	11100
Hexadecimal	1C

Aleph-0, the smallest infinite cardinal In mathematics, cardinal numbers, or cardinals for short, are a generalized kind of number used to denote the size of a set. ... Commonly, ordinal numbers, or ordinals for short, are numbers used to denote the position in an ordered sequence: first, second, third, fourth, etc. ... In mathematics, factorization or factoring is the decomposition of an object (for example, a number, a polynomial, or a matrix) into a product of other objects, or factors, which when multiplied together give the original. ... In mathematics, a divisor of an integer n, also called a factor of n, is an integer which evenly divides n without leaving a remainder. ... The system of Roman numerals is a numeral system originating in ancient Rome, and was 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. ... In mathematics and computer science, hexadecimal, base-16, or simply hex, is a numeral system with a radix, or base, of 16, usually written using the symbols 0–9 and A–F, or a–f. ...

In mathematics

It is a composite number, its proper divisors being 1, 2, 4, 7, and 14, making it a perfect number and a harmonic divisor number. 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 leaving a remainder. ... Look up one in Wiktionary, the free dictionary. ... II redirects here. ... This article discusses the number Four. ... Seven Days of Creation - 1765 book, title page Seven (7) is the sixth successor of one (1). ... 14 (fourteen) is the natural number following 13 and preceding 15. ... In mathematics, a perfect number is defined as an integer which is the sum of its proper positive divisors, that is, the sum of the positive divisors not including the number. ... A harmonic divisor number, or Ore number, is a number whose divisors, averaged in a harmonic mean, results in an integer. ...

Twenty-eight is the second perfect number. As a perfect number, it is related to the Mersenne prime 7, since 2²(2³ - 1) = 28. The next perfect number is 496, the previous being 6. In mathematics, a perfect number is defined as an integer which is the sum of its proper positive divisors, that is, the sum of the positive divisors not including the number. ... In mathematics, a Mersenne number is a number that is one less than a power of two. ... Four hundred and ninety-six is the natural number following four hundred and ninety-five and preceding four hundred and ninety-seven. ... Number 6, in this article, refers to the mathematical number. ...

Twenty-eight is a triangular number, a hexagonal number, a happy number and a centered nonagonal number. Twenty-eight is the sum of the first five prime numbers, and the sum of the toilet function for the first nine integers. A triangular number is a natural number such that the shape of an equilateral triangle can be formed by that number of points. ... A hexagonal number is a figurate number that represents a hexagon. ... Consider the following process: given a number, take the sum of the squares of its digits. ... A centered nonagonal number is a centered figurate number that represents a nonagon with a dot in the center and all other dots surrounding the center dot in successive nonagonal layers. ... In mathematics, a prime number, or prime for short, is a natural number greater than one and whose only distinct positive divisors are 1 and itself. ...

It appears in the Padovan sequence, preceded by the terms 12, 16, 21 (it is the sum of the first two of these). The Padovan sequence is the sequence of integers P(n) defined by the initial values and the recurrence relation The first few values of P(n) are 1, 1, 1, 2, 2, 3, 4, 5, 7, 9, 12, 16, 21, 28, 37, 49, 65, 86, 144, 151, 200. ...

It is also a Keith number, because it recurs in a Fibonacci-like sequence started from its base 10 digits: 2, 8, 10, 18, 28... In mathematics, a Keith number or repfigit number is an integer that appears as a term in a linear recurrence relation with initial terms based off its own digits. ... Drawing of Leonardo Pisano Leonardo of Pisa or Leonardo Pisano (Pisa, c. ...

Twenty-eight is the ninth and last number in early Indian Magic square of order 3. It has been suggested that Date magic square be merged into this article or section. ...

There are twenty-eight convex uniform honeycombs. In geometry, a convex uniform honeycomb is a uniform space-filling tessellation in three-dimensional Euclidean space with non-overlapping convex uniform polyhedral cells. ...

In science

• The atomic number of nickel
• The fourth Magic number (physics)

It has been suggested that List of elements by atomic number be merged into this article or section. ... General Name, Symbol, Number nickel, Ni, 28 Chemical series transition metals Group, Period, Block 10, 4, d Appearance lustrous, metallic and silvery with a gold tinge Atomic mass 58. ... In nuclear physics, a magic number is a number of nucleons such that they are arranged into complete shells within the atomic nucleus. ...

Astronomy

• Messier object M28, a magnitude 8.5 globular cluster in the constellation Sagittarius

• The New General Catalogue object NGC 28, an elliptical galaxy in the constellation Phoenix

• The Saros number of the solar eclipse series which began on -1910 March 22 and ended on -630 April 28. The duration of Saros series 28 was 1280.1 years, and it contained 72 solar eclipses.

• The Saros number of the lunar eclipse series which began on -1915 June 27 and ended on -581 September 6. The duration of Saros series 28 was 1334.2 years, and it contained 75 lunar eclipses.

• The planet Saturn revolves around the Sun in approximately 28 years. This is acknowledged in Astrology and in cultures or religions that base partly on it (see below, other fields)

The Messier objects are a set of astronomical objects catalogued by Charles Messier in his catalogue of Nebulae and Star Clusters first published in 1774. ... Globular Cluster M28 (also known as Messier Object 28, Messier 28, M28, or NGC 6626) is a globular cluster in the Sagittarius constellation. ... The apparent magnitude (m) of a star, planet or other heavenly body is a measure of its apparent brightness; that is, the amount of light received from the object. ... The Globular Cluster M80 in the constellation Scorpius is located about 28,000 light years from the Sun and contains hundreds of thousands of stars. ... This article or section does not cite its references or sources. ... For other uses, see Sagittarius. ... The New General Catalogue (NGC) is the most well-known catalogue of deep sky objects in amateur astronomy. ... An elliptical galaxy is a type of galaxy in the Hubble sequence characterized by the following physical properties: The giant elliptical galaxy NGC 4881 (the spherical glow at upper left) lies at the edge of the Coma Cluster of Galaxies. ... Categories: Astronomy stubs | Modern constellations | Constellations ... A Saros cycle is a period of 6585 + 1/3 days (approximately 18 years 10 days and 8 hours) which can be used to predict eclipses of the sun and the moon. ... Photo taken during the 1999 eclipse. ... March 22 is the 81st day of the year in the Gregorian Calendar (82nd in leap years). ... April 28 is the 118th day of the year (119th in leap years) in the Gregorian Calendar, with 247 days remaining. ... A lunar eclipse occurs whenever the Moon passes through some portion of the Earths shadow. ... June 27 is the 178th day of the year (179th in leap years) in the Gregorian calendar, with 187 days remaining. ... September 6 is the 249th day of the year (250th in leap years). ... The eight planets and three dwarf planets of the Solar System. ... Note: This article contains special characters. ... The Sun is the star at the center of the Solar System. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... Hand-coloured version of the anonymous Flammarion woodcut. ...

In other fields

Twenty-eight is:

• The number of days in the shortest month of the Gregorian calendar, February (except in leap years, when there are twenty-nine). All twelve months of the Gregorian calendar have at least 28 days, regardless of the year.
• Years normally follow a 28-year cycle, since there are seven days in a week and leap year occurs every four years; a calendar from 28 years ago is the same as this year's (a year like 1900, non-leap though divisible by four, breaks the pattern).
• The common name for the parrot 'Barnardius zonarius semitorquatus', widely distributed in Western Australia and South Australia. Its call sounds like "wenniate".
• The number of letters in the Danish and Swedish alphabets (not counting W), and also in the Arabic and Esperanto alphabets.
• In neo-Nazi circles, twenty-eight indicates Blood and Honour (28 = BH - B - second letter of the alphabet and H - the eight letter).
• Part of the title of a romantic comedy movie 28 Days, and an unrelated science fiction movie 28 Days Later.
• Part of the name of a well known indie rock band from Melbourne, Australia called 28 Days - the name is unrelated to either of the movies above.
• The number of Chinese constellations, "Xiu" or "mansions" (a literal translation), equivalent to the 12 western zodiac constellations.
• The number of normal human teeth, not including the third molars (wisdom teeth).
• The number of dominoes in standard domino sets.
• Deriving from the 28 year cycle of Saturns revolution around the Sun, the 28-year cycle as well as its subdivisions by 14 and 7 are supposed in Astrology to mark significant turning points or sections in the course of a persons development in life. Thus, the number 28 has special significance in the culture of religious sects such as the Kadiri and the Mevlevi dervishes. The 28-beat metric pattern often used in the music compositions accompanying the main part of the Mevlevi sema ritual is called the "Devri kebir", meaning the "Big Circle" and is a reference to above astronomical facts about the year and the Saturn year.
• In Québec, François Pérusse, in one of his best-selling Album du peuple made a parody of Wheel of fortune in which all of the letters picked by the contestant were present 28 times. As a result, 28 became an almost Mythical number used by many Québec youths, the phrase "Y'en a 28" (There are 28 [Letters]) became a running gag still used and recognized more than 15 years later.
• The Preludes, Opus 28 consists of Frédéric Chopin's 24 preludes for piano, ordinarily but not necessarily played together in concert.
• The postal code of the province of Madrid, in Spain.
• Twenty Eight is a popular game played in Kerala India.
• 28 is the number worn by Peterborough Phantoms forward Steve Maile

Look up Month in Wiktionary, the free dictionary. ... The Gregorian calendar is the most widely used calendar in the world. ... For other uses, see February (disambiguation). ... A Leap Year (or intercalary year) is a year containing an extra day (or, in case of lunisolar calendars, an extra month) in order to keep the calendar year synchronised with the astronomical or seasonal year. ... It has been suggested that True parrots be merged into this article or section. ... Binomial name Barnardius zonarius (Shaw, 1805) subspecies Synonyms Barnardius barnardi (Vigors & Horsfield, 1827) The Australian Ringneck (Barnardius zonarius) is a parrot native to all mainland Australian states. ... Capital Perth Government Constitutional monarchy Governor Ken Michael Premier Alan Carpenter (ALP) Federal representation  - House seats 15  - Senate seats 12 Gross State Product (2004-05)  - Product ($m)  $100,900 (4th)  - Product per capita  $50,355/person (3rd) Population (December 2006)  - Population  2,050,900 (4th)  - Density  0. ... Capital Adelaide Government Constitutional monarchy Governor Marjorie Jackson-Nelson Premier Mike Rann (ALP) Federal representation  - House seats 11  - Senate seats 12 Gross State Product (2004-05)  - Product ($m)  $59,819 (5th)  - Product per capita  $38,838/person (7th) Population (End of March 2005)  - Population  1,540,200 (5th)  - Density  1. ... A Specimen of typeset fonts and languages, by William Caslon, letter founder; from the 1728 Cyclopaedia. ... The Arabic alphabet is the script used for writing Arabic and various other languages, together with various closely related scripts that typically differ in the presence or absence of a few letters. ... Esperanto is written in a Latin alphabet of twenty-eight letters, upper and lower case. ... A Specimen of typeset fonts and languages, by William Caslon, letter founder; from the 1728 Cyclopaedia. ... YES YES ... In the film, Gwen Cummings (Bullock) is a party animal, constantly high on either alcohol or some form of barbiturates. ... 28 Days Later is a 2002 post-apocalyptic science fiction film directed by Danny Boyle and written by Alex Garland. ... Melbournes CBD has grown to straddle the Yarra River in three major precincts. ... This article or section does not cite its references or sources. ... It has been suggested that this article be split into multiple articles. ... Wisdom teeth are third molars that usually appear between the ages of 17 and 24 (although they may appear when older, younger, or may not appear at all). ... A game of Dominoes Dominoes (or dominos) generally refers to the individual or collective gaming pieces making up a domino set (sometimes called a deck or pack) or to the games played with these pieces. ... Note: This article contains special characters. ... The Sun is the star at the center of the Solar System. ... Hand-coloured version of the anonymous Flammarion woodcut. ... Headline text KADIRI A small town in Anantapur District. ... Whirling Dervishes perform near the Mevlevi Museum in Konya, Turkey. ... Whirling Dervishes perform near the Mevlevi Museum in Konya, Turkey. ... Specialty Equipment Market Association (SEMA ) of the automobile aftermarket was formed in 1963 by Roy Richter, Ed Iskenderian, Willie Garner, Bob Hedman, John Bartlett, Phil Weiand, Jr. ... During the 1960s, a terrorist group known as the Front de libération du Québec (FLQ) launched a decade of bombings, robberies and attacks on government offices. ... François Pérusse is a Québécois humorist and singer famous for his radio sketches featuring puns and absurd humor. ... This article discusses the current version of the U.S. game show. ... A mythical number is a number used and accepted as deriving from scientific investigation and/or careful selection, but whose origin is unknown and whose basis is unsubstantiated. ... The running gag is a popular hallmark of comic and serious forms of entertainment. ... The Preludes Op. ... Fryderyk Franciszek Chopin (French: Frédéric François Chopin; English: IPA: or ; French: ) (March 1, 1810[1] â€“ October 17, 1849) was a Polish pianist and composer of the Romantic era. ... Postal codes are generally clearly visible outside local Australian post offices. ... Capital Madrid Official language(s) Spanish Area  â€“ Total  â€“ % of Spain Ranked 12th  8,030. ... This is one of a group of South Asian trick-taking games in which the Jack and the Nine are the highest cards in every suit. ... League: EPIHL Founded: 2002 Home Ice: Planet Ice Peterborough Capacity: 1250 Ice Size: 180ft x 85ft City: Peterborough, United Kingdom Colours: Blue, Silver, White, and Black Captain: Lewis Buckman Head Coach: Doug McEwen Ownership: Phil Wing and Rob Housden Website: peterborough-phantoms. ...

Historical years

28 A.D., 28 B.C., 1928, 2028, etc. For other uses, see number 28. ... Centuries: 2nd century BC - 1st century BC - 1st century Decades: 70s BC 60s BC 50s BC 40s BC 30s BC - 20s BC - 10s BC 0s 10s 20s 30s Years: 33 BC 32 BC 31 BC 30 BC 29 BC 28 BC 27 BC 26 BC 25 BC 24 BC 23... Year 1928 (MCMXXVIII) was a leap year starting on Sunday (link will display full calendar). ... 2028 (MMXXVIII) will be a leap year starting on Saturday of the Gregorian Calendar. ...