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84 (number)
Encyclopedia
84 is the natural number
following 83
and preceding 85
.
Eighty-four is the sum of the first seven triangular number
s (making it a tetrahedral number
), as well as the sum of a twin prime
(41 + 43). Being thrice a perfect number, 84 is itself a semiperfect number
.
Eighty-four is also the lim sup of the largest finite subgroup of the mapping class group
of a genus
surface divided by 
.
A hepteract
is a seven-dimension
al hypercube
with 84 penteract
5-faces
Magic Johnson
holds the record for assists in a 6-game NBA Finals Series (1985) with 84
Eighty-four is also:
Natural number
In mathematics, the natural numbers are the ordinary whole numbers used for counting and ordering . These purposes are related to the linguistic notions of cardinal and ordinal numbers, respectively...
following 83
83 (number)
83 is the natural number following 82 and preceding 84.-In mathematics:Eighty-three is the sum of three consecutive primes as well as the sum of five consecutive primes ....
and preceding 85
85 (number)
85 is the natural number following 84 and preceding 86.-In mathematics:85 is an octahedral number, a centered triangular number, a centered square number, a decagonal number, and a Smith number....
.
In mathematics
Triangular number
A triangular number or triangle number numbers the objects that can form an equilateral triangle, as in the diagram on the right. The nth triangle number is the number of dots in a triangle with n dots on a side; it is the sum of the n natural numbers from 1 to n...
s (making it a tetrahedral number
Tetrahedral number
A tetrahedral number, or triangular pyramidal number, is a figurate number that represents a pyramid with a triangular base and three sides, called a tetrahedron...
), as well as the sum of a twin prime
Twin prime
A twin prime is a prime number that differs from another prime number by two. Except for the pair , this is the smallest possible difference between two primes. Some examples of twin prime pairs are , , , , and...
(41 + 43). Being thrice a perfect number, 84 is itself a semiperfect number
Semiperfect number
In number theory, a semiperfect number or pseudoperfect number is a natural number n that is equal to the sum of all or some of its proper divisors. A semiperfect number that is equal to the sum of all its proper divisors is a perfect number....
.
Eighty-four is also the lim sup of the largest finite subgroup of the mapping class group
Mapping class group
In mathematics, in the sub-field of geometric topology, the mapping class groupis an important algebraic invariant of a topological space. Briefly, the mapping class group is a discrete group of 'symmetries' of the space.-Motivation:...
of a genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
surface divided by .A hepteract
Hepteract
In geometry, a 7-cube is a seven-dimensional hypercube with 128 vertices, 448 edges, 672 square faces, 560 cubic cells, 280 tesseract 4-faces, 84 penteract 5-faces, and 14 hexeract 6-faces....
is a seven-dimension
Dimension
In physics and mathematics, the dimension of a space or object is informally defined as the minimum number of coordinates needed to specify any point within it. Thus a line has a dimension of one because only one coordinate is needed to specify a point on it...
al hypercube
Hypercube
In geometry, a hypercube is an n-dimensional analogue of a square and a cube . It is a closed, compact, convex figure whose 1-skeleton consists of groups of opposite parallel line segments aligned in each of the space's dimensions, perpendicular to each other and of the same length.An...
with 84 penteract
Penteract
In five dimensional geometry, a 5-cube is a name for a five dimensional hypercube with 32 vertices, 80 edges, 80 square faces, 40 cubic cells, and 10 tesseract hypercells....
5-faces
In astronomy
- Messier objectMessier objectThe Messier objects are a set of astronomical objects first listed by French astronomer Charles Messier in 1771. The original motivation of the catalogue was that Messier was a comet hunter, and was frustrated by objects which resembled but were not comets...
M84Messier 84Messier 84 is a lenticular galaxy in the constellation Virgo. M84 is situated in the heavily populated inner core of the Virgo Cluster of galaxies....
, a magnitude 11.0 lenticular galaxyLenticular galaxyA lenticular galaxy is a type of galaxy which is intermediate between an elliptical galaxy and a spiral galaxy in galaxy morphological classification schemes. Lenticular galaxies are disk galaxies which have used up or lost most of their interstellar matter and therefore have very little ongoing...
in the constellationConstellationIn modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
VirgoVirgo (constellation)Virgo is one of the constellations of the zodiac. Its name is Latin for virgin, and its symbol is . Lying between Leo to the west and Libra to the east, it is the second largest constellation in the sky... - The New General CatalogueNew General CatalogueThe New General Catalogue of Nebulae and Clusters of Stars is a well-known catalogue of deep sky objects in astronomy. It contains 7,840 objects, known as the NGC objects...
object NGC 84, a single star in the constellation AndromedaAndromeda (constellation)Andromeda is a constellation in the northern sky. It is named after Andromeda, the princess in the Greek legend of Perseus who was chained to a rock to be eaten by the sea monster Cetus... - The SarosSaros cycleThe saros is a period of 223 synodic months , that can be used to predict eclipses of the Sun and Moon. One saros after an eclipse, the Sun, Earth, and Moon return to approximately the same relative geometry, and a nearly identical eclipse will occur, in what is referred to as an eclipse cycle...
number of the solar eclipseSolar eclipseAs seen from the Earth, a solar eclipse occurs when the Moon passes between the Sun and the Earth, and the Moon fully or partially blocks the Sun as viewed from a location on Earth. This can happen only during a new moon, when the Sun and the Moon are in conjunction as seen from Earth. At least...
series which began on -181 April 14 and ended on 1099 May 22. The duration of Saros series 84 was 1280.1 years, and it contained 72 solar eclipses. Further, the number of the lunar eclipseLunar eclipseA lunar eclipse occurs when the Moon passes behind the Earth so that the Earth blocks the Sun's rays from striking the Moon. This can occur only when the Sun, Earth, and Moon are aligned exactly, or very closely so, with the Earth in the middle. Hence, a lunar eclipse can only occur the night of a...
series which began on -96 September 13 and ended on 1401 February 28. The duration of Saros series 84 was 1496.5 years, and it contained 84 lunar eclipses.
In sports
Los Angeles LakersLos Angeles Lakers
The Los Angeles Lakers are an American professional basketball team based in Los Angeles, California. They play in the Pacific Division of the Western Conference in the National Basketball Association...
Magic Johnson
Magic Johnson
Earvin "Magic" Johnson Jr. is a retired American professional basketball player who played point guard for the Los Angeles Lakers of the National Basketball Association . After winning championships in high school and college, Johnson was selected first overall in the 1979 NBA Draft by the Lakers...
holds the record for assists in a 6-game NBA Finals Series (1985) with 84
In other fields
- The year AD 84, 84 BC84 BCYear 84 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Carbo and Cinna...
, or 1984. - The atomic numberAtomic numberIn chemistry and physics, the atomic number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus. It is conventionally represented by the symbol Z. The atomic number uniquely identifies a chemical element...
of poloniumPoloniumPolonium is a chemical element with the symbol Po and atomic number 84, discovered in 1898 by Marie Skłodowska-Curie and Pierre Curie. A rare and highly radioactive element, polonium is chemically similar to bismuth and tellurium, and it occurs in uranium ores. Polonium has been studied for... - The model number of Harpoon missile
- WGS 84 - The latest revision of the World Geodetic SystemWorld Geodetic SystemThe World Geodetic System is a standard for use in cartography, geodesy, and navigation. It comprises a standard coordinate frame for the Earth, a standard spheroidal reference surface for raw altitude data, and a gravitational equipotential surface that defines the nominal sea level.The latest...
, a fixed global reference frame for the Earth. - The house number of 84 Avenue Foch84 Avenue FochNumber 84 Avenue Foch was a building in Paris used by the Gestapo during the German occupation of Paris in World War II.The location is found on Avenue Foch, a wide residential boulevard in the XVIe arrondissement which connects the Arc de Triomphe and the Porte Dauphine.During the German...
- The number of the French department VaucluseVaucluseThe Vaucluse is a department in the southeast of France, named after the famous spring, the Fontaine-de-Vaucluse.- History :Vaucluse was created on 12 August 1793 out of parts of the departments of Bouches-du-Rhône, Drôme, and Basses-Alpes...
- The designation of Interstate 84, two Interstate Highways that run from OregonOregonOregon is a state in the Pacific Northwest region of the United States. It is located on the Pacific coast, with Washington to the north, California to the south, Nevada on the southeast and Idaho to the east. The Columbia and Snake rivers delineate much of Oregon's northern and eastern...
to UtahUtahUtah is a state in the Western United States. It was the 45th state to join the Union, on January 4, 1896. Approximately 80% of Utah's 2,763,885 people live along the Wasatch Front, centering on Salt Lake City. This leaves vast expanses of the state nearly uninhabited, making the population the...
and from PennsylvaniaPennsylvaniaThe Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to...
to MassachusettsMassachusettsThe Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
. - The code for international direct dial phone calls to VietnamVietnamVietnam – sometimes spelled Viet Nam , officially the Socialist Republic of Vietnam – is the easternmost country on the Indochina Peninsula in Southeast Asia. It is bordered by China to the north, Laos to the northwest, Cambodia to the southwest, and the South China Sea –...
- The town of Eighty FourEighty Four, PennsylvaniaEighty Four is a small unincorporated community mostly within Somerset Township in Washington County, Pennsylvania, United States. It lies approximately 25 miles southwest of Pittsburgh and is in the Pittsburgh metropolitan area....
, PennsylvaniaPennsylvaniaThe Commonwealth of Pennsylvania is a U.S. state that is located in the Northeastern and Mid-Atlantic regions of the United States. The state borders Delaware and Maryland to the south, West Virginia to the southwest, Ohio to the west, New York and Ontario, Canada, to the north, and New Jersey to... - The company 84 Lumber84 Lumber84 Lumber is an American building materials chain. 84 Lumber Company is the largest privately held building materials supplier to professional contractors in the country. Headquartered in the Pittsburgh Metro Area town of Eighty Four, Pennsylvania, it was founded in 1956 by Joseph Hardy...
- The ISBN Group Identifier for books published in SpainSpainSpain , officially the Kingdom of Spain languages]] under the European Charter for Regional or Minority Languages. In each of these, Spain's official name is as follows:;;;;;;), is a country and member state of the European Union located in southwestern Europe on the Iberian Peninsula...
- A variation of the gameGameA game is structured playing, usually undertaken for enjoyment and sometimes used as an educational tool. Games are distinct from work, which is usually carried out for remuneration, and from art, which is more often an expression of aesthetic or ideological elements...
4242 (dominoes)42, also known as Texas 42, is a trick-taking game played with a standard set of double six dominoes. 42 is often referred to as the "national game of Texas", and continues to be very popular in much of the state. Tournaments are held in many towns, and the State Championship tournament is held...
played with two sets of dominoesDominoesDominoes generally refers to the collective gaming pieces making up a domino set or to the subcategory of tile games played with domino pieces. In the area of mathematical tilings and polyominoes, the word domino often refers to any rectangle formed from joining two congruent squares edge to edge...
. - The film "84 Charing Cross Road84 Charing Cross Road84, Charing Cross Road is a 1970 book by Helene Hanff, later made into a stage play, television play and film, about the twenty-year correspondence between her and Frank Doel, chief buyer of Marks & Co, antiquarian booksellers located at the eponymous address in London, England.Hanff, in search of...
" (1987) starring Anne BancroftAnne BancroftAnne Bancroft was an American actress associated with the Method acting school, which she had studied under Lee Strasberg....
and Anthony HopkinsAnthony HopkinsSir Philip Anthony Hopkins, KBE , best known as Anthony Hopkins, is a Welsh actor of film, stage and television... - KKNXKKNXKKNX is an oldies radio station broadcasting to the Eugene, Oregon area on 840 AM....
Radio 84 in Eugene, OregonEugene, OregonEugene is the second largest city in the U.S. state of Oregon and the seat of Lane County. It is located at the south end of the Willamette Valley, at the confluence of the McKenzie and Willamette rivers, about east of the Oregon Coast.As of the 2010 U.S... - The John Larroquette ShowThe John Larroquette ShowThe John Larroquette Show is a situation comedy that ran on the NBC network from 1993 to 1996. The show, created by Don Reo, was a vehicle for John Larroquette following his run as Dan Fielding on Night Court. The series took place in a seedy bus terminal in St. Louis, Missouri and focused on the...
ran on NBCNBCThe National Broadcasting Company is an American commercial broadcasting television network and former radio network headquartered in the GE Building in New York City's Rockefeller Center with additional major offices near Los Angeles and in Chicago...
from 1993 to 1996 for 84 episodes - The B-Side to "Up All Night" (Take That song)Up All Night (Take That song)"Up All Night" is the second single from British group Take That's fifth studio album, The Circus.-Song information:Released on 2 March 2009, it was the second single from the album The Circus. The single was only released in the UK and Ireland. The band performed "Up All Night" on Ant and Dec's...
- British Army term for the 84mm Carl Gustav recoilless rifleCarl Gustav recoilless rifleThe Carl Gustav is the common name for the 84 mm man-portable reusable multi-role recoilless rifle produced by Saab Bofors Dynamics in Sweden...
.