68 (number)
Encyclopedia
68 is the natural number
following 67
and preceding 69
.
. It is also a Perrin number
, preceded in the sequence by 29, 39, 51 (it is the sum of the first two mentioned). It is also a Happy number
.
In normal distribution, 68% of values are within one standard deviation from the mean; see 68-95-99.7 rule
.
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 67
67 (number)
67 is the natural number following 66 and preceding 68. It is an odd number.-In mathematics:Sixty-seven is the 19th prime number , an irregular prime, a lucky prime, the sum of five consecutive primes , and a Heegner number.Since 18! + 1 is divisible by 67 but 67 is not one more than a multiple of...
and preceding 69
69 (number)
69 is a number following 68 and preceding 70.- In mathematics:The aliquot sum of sixty-nine is 27 within the aliquot sequence 69 being the third composite number in the 13-aliquot tree.69 is a semiprime...
.
In mathematics
Sixty-eight is a nontotientNontotient
In number theory, a nontotient is a positive integer n which is not in the range of Euler's totient function φ, that is, for which φ = n has no solution. In other words, n is a nontotient if there is no integer x that has exactly n coprimes below it. All odd numbers are nontotients, except 1,...
. It is also a Perrin number
Perrin number
In mathematics, the Perrin numbers are defined by the recurrence relationandThe sequence of Perrin numbers starts withThe number of different maximal independent sets in an n-vertex cycle graph is counted by the nth Perrin number.-History:...
, preceded in the sequence by 29, 39, 51 (it is the sum of the first two mentioned). It is also a Happy number
Happy number
A happy number is defined by the following process. Starting with any positive integer, replace the number by the sum of the squares of its digits, and repeat the process until the number equals 1 , or it loops endlessly in a cycle which does not include 1...
.
In normal distribution, 68% of values are within one standard deviation from the mean; see 68-95-99.7 rule
68-95-99.7 rule
In statistics, the 68-95-99.7 rule, or three-sigma rule, or empirical rule, states that for a normal distribution, nearly all values lie within 3 standard deviations of the mean....
.
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...
M68Messier 68Messier 68 is a globular cluster in the Hydra constellation. It was discovered by Charles Messier in 1780. M68 is at a distance of about 33,000 light-years away from Earth.-External links:* *...
, a magnitude 9.0 globular clusterGlobular clusterA globular cluster is a spherical collection of stars that orbits a galactic core as a satellite. Globular clusters are very tightly bound by gravity, which gives them their spherical shapes and relatively high stellar densities toward their centers. The name of this category of star cluster is...
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....
HydraHydra (constellation)Hydra is the largest of the 88 modern constellations, measuring 1303 square degrees. It has a long history, having been included among the 48 constellations listed by the 2nd century astronomer Ptolemy. It is commonly represented as a water snake...
- 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 68, a spiral galaxySpiral galaxyA spiral galaxy is a certain kind of galaxy originally described by Edwin Hubble in his 1936 work The Realm of the Nebulae and, as such, forms part of the Hubble sequence. Spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as...
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 Saros 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 -626 March 16 and ended on 685 August. The duration of Saros series 68 was 1280.1 years, and it contained 72 solar eclipses.
- The Saros 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 -613 July 3 and ended on 685 August. The duration of Saros series 68 was 1298.1 years, and it contained 73 lunar eclipses.
In other fields
Sixty-eight is:- In degrees Fahrenheit, the ideal temperature for developing black-and-whiteBlack-and-whiteBlack-and-white, often abbreviated B/W or B&W, is a term referring to a number of monochrome forms in visual arts.Black-and-white as a description is also something of a misnomer, for in addition to black and white, most of these media included varying shades of gray...
filmFilmA film, also called a movie or motion picture, is a series of still or moving images. It is produced by recording photographic images with cameras, or by creating images using animation techniques or visual effects... - The designation of US Interstate 68Interstate 68Interstate 68 is a Interstate highway in the U.S. states of West Virginia and Maryland, connecting in Morgantown to in Hancock. is also Corridor E of the Appalachian Development Highway System. From 1965 until the freeway's construction was completed in 1991, it was designated as...
, a freeway that runs from West VirginiaWest VirginiaWest Virginia is a state in the Appalachian and Southeastern regions of the United States, bordered by Virginia to the southeast, Kentucky to the southwest, Ohio to the northwest, Pennsylvania to the northeast and Maryland to the east...
to MarylandMarylandMaryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east... - The registry of the U.S. Navy's aircraft carrier USS Nimitz (CVN-68), named after Admiral Chester NimitzChester NimitzFleet Admiral Chester William Nimitz, GCB, USN was a five-star admiral in the United States Navy. He held the dual command of Commander in Chief, United States Pacific Fleet , for U.S. naval forces and Commander in Chief, Pacific Ocean Areas , for U.S...
- The number of the French department Haut-RhinHaut-RhinHaut-Rhin is a département of the Alsace region of France, named after the Rhine river. Its name means Upper Rhine. Haut-Rhin is the smaller and less populated of the two departements of Alsace, although is still densely populated compared to the rest of France.-Subdivisions:The department...
- A publishing house in Canada for exiled Czech authors, 68 Publishers68 Publishers68 Publishers, also called Sixty-Eight Publishers, Sixtyeight Publishers, or even Nakladatelství 68 , was a publishing house formed in Toronto in 1971 by Czech expatriate Josef Škvorecký and his wife Zdena Salivarová...
- In the restaurant industry, it may can mean "put on order", being the opposite of 86 (number)86 (number)86 is the natural number following 85 and preceding 87.-In mathematics:86 is the 25th distinct semiprime and the 13th of the form...
which means "take away" - The number of sectors on one cylinder of MFMModified Frequency ModulationModified Frequency Modulation, commonly MFM, is a line coding scheme used to encode the actual data-bits on most floppy disk formats, hardware examples include Amiga, most CP/M machines as well as IBM PC compatibles. Early hard disk drives also used this coding.MFM is a modification to the original...
hard disks with 4 heads and 17 sectors per track - A reference to the Prague SpringPrague SpringThe Prague Spring was a period of political liberalization in Czechoslovakia during the era of its domination by the Soviet Union after World War II...
of 1968 in CzechoslovakiaCzechoslovakiaCzechoslovakia or Czecho-Slovakia was a sovereign state in Central Europe which existed from October 1918, when it declared its independence from the Austro-Hungarian Empire, until 1992... - "Summer '68Summer '68"Summer '68" is a song by Pink Floyd on their album Atom Heart Mother. Written and sung by Richard Wright, it is about a one night stand, and the return to habitual life. The soft piano intro contrasts with the bombastic trumpet solo breaks in the middle and end of the song, the latter breaks...
" is a song by Pink FloydPink FloydPink Floyd were an English rock band that achieved worldwide success with their progressive and psychedelic rock music. Their work is marked by the use of philosophical lyrics, sonic experimentation, innovative album art, and elaborate live shows. Pink Floyd are one of the most commercially...
on the album Atom Heart MotherAtom Heart MotherAtom Heart Mother is the fifth studio album by English progressive rock band Pink Floyd, released in 1970 by Harvest and EMI Records in the United Kingdom and Harvest and Capitol in the United States. It was recorded at Abbey Road Studios, London, England, and reached number one in the United...