7 (number)
7 (
seven) is the
natural number following
6 and preceding
8.
The
SI prefix for 1000
7 is
zetta (Z), and for its reciprocal
zepto (z).
*Seven is the
fourth prime number.
*Seven is a
Mersenne prime, since 2
3 - 1 = 7.
*Seven is the fourth
Mersenne prime exponent.
*Seven is the first
Newman-Shanks-Williams prime.
*Seven is the third
Lucas prime.
*Seven is the first
Woodall prime.
*Seven is the second
lucky prime.
*Seven is the second
safe prime.
*Seven is the fourth
factorial prime*Seven is both a
Carol number and a
Kynea number.
*Seven is the smallest number that can't be represented as a sum of fewer than four nonzero squares.
*Seven is a
self number.
*Seven is the smallest
happy number, except for the trivial example of 1.
*Although the
divisible by seven (7) test is not well known (especially compared to the popular
divisible by three (3) test), there is an easy way to test if a natural number is evenly
divisible by seven (7). See also
Divisibility rule.:# Remove the last digit,:# Double it, and:# Subtract it from the remaining digits.:# If the result is negative and there are 2 or more digits, drop the negative sign.:# Repeat until you end up with a result that is a multiple of seven (7). (i.e. -7, 0, or +7):For example, the number 1358 is evenly divisible by seven, since:::135 - (8*2) = 119::11 - (9*2) = -7:Using
Number Theory the proof is rather easy, once we rewrite the number
n in the form:::n = 10
a +
bWhere:::
a is the remaining digits, and::
b is the last digit.
Then:::10a + b = 0 (mod 7)::5 * (10a + b) = 0 (mod 7)::49a + a + 5b = 0 (mod 7)::a + 5b - 7b = 0 (mod 7)::a - 2b = 0 (mod 7)
*
999,999 divided by 7 is exactly
142,857, so
vulgar fractions with 7 in the
denominator have six-
digit repeating sequences in their
decimal expansions. 1/7 = 0.142857142....
*A seven-sided
polygon is a
heptagon. The regular
n-gons for
n ≤ 6 can be constructed by
compass and straightedge alone, but the regular heptagon cannot.
Figurate numbers representing heptagons (including seven) are called
heptagonal numbers. Seven is also a
centered hexagonal number.
*There are seven
frieze groups, the
groups consisting of
symmetries of the plane whose group of
translations is
isomorphic to the group of
integers.
*A group or a series of seven is a
heptad.
*7 is the only dimension, besides the familiar 3, in which a vector
cross product can be defined.
In numeral systems
In quaternary, 7 is the smallest prime with a composite sum of digits.
 |
Evo7glyph.png |
In the beginning, various
Hindus wrote 7 more or less in one stroke as a curve that looks like an
uppercase J upside down. The western Ghubar Arabs' main contribution was to make the longer line diagonal rather than straight, though they showed some tendencies to making the
character more rectilinear. The eastern
Arabs developed the character from a 6-look-alike into an uppercase V-look-alike. Both modern Arab forms influenced the European form, a two-stroke character consisting of a horizontal upper line joined at its right to a line going down to the bottom left corner, a line that is slightly curved in some font variants. As is the case with the
European glyph, the Cham and Khmer glyph for 7 also
evolved to look like their glyph for 1, though in a different way, and so they were also concerned with making their 7 more different. For the Khmer this often involved adding a horizontal line above the glyph. This is analogous to the horizontal stroke through the middle that is sometimes used in handwriting in the Western world but which is almost never used in computer fonts. This horizontal stroke is, however, important to distinguish the glyph for seven from the glyph for
one in writings that use a long upstroke in the glyph for
one.
 |
Digital7sL.png |
On the
seven-segment displays of pocket calculators and digital watches, 7 is the number with the most common glyph variation (0, 6 and 9 also have variant glyphs). Most calculators use three line segments, but on
Sharp,
Casio and a few other brands of calculators, 7 is written with four line segments.The reason is that 7 is written as in ① in Japan,Korea and so on.
In fonts with
text figures, 7 usually has a descender, for example,
 |
TextFigs078.png |
.
* The number of spots in a common
ladybug.
Chemistry
* The
atomic number of
nitrogen.
* The number of periods, or horizontal rows of
elements, on the
periodic table.
* The number of
carbon atoms in
heptane, a
hydrocarbon.
* The neutral
pH - the pH level of pure water.
Astronomy
*The number of objects in the
solar system visible to the naked eye — the
Sun, the
Moon and the five classical
naked eye planets:
Mars,
Mercury,
Jupiter,
Venus, and
Saturn.
*
Messier object M7, a magnitude 3.5
open cluster in the constellation
Scorpius.
*The
New General Catalogue object NGC 7, a 14th
magnitude spiral
galaxy in the
constellation Sculptor*The seven daughters of
Atlas in the
Pleiades (also called the "
seven sisters").
*The number of saints appear in a constellation called "Saptharishi Mandalam" in Indian astronomy.
*The number of stars in the constellation of
Ursa major.
*The
Saros number of the
solar eclipse series which began on
-2590 April 8 and ended on
-1310 May 16. The duration of Saros series 7 was 1280.1 years, and it contained 72 solar eclipses.
*The Saros
number of the
lunar eclipse series which began on
-2595 July 15 and ended on
-1008 February 22. The duration of Saros series 7 was 1586.6 years, and it contained 89 lunar eclipses.
* The Roman numeral VII stands for
white dwarfs in the
Yerkes spectral classification scheme.
* The Roman numeral VII (usually) stands for the seventh-discovered satellite of a planet or minor planet (e.g.
Jupiter VII)
* A highly symbolic number in the
Torah, alluding to the infusion of spirituality and Godliness into the
Creation. For example:#
God rested on and sanctified the 7th day (
Shabbat)#A seven-day
purification period is required for one who has become
tamei to become
tahor#The
Shemittah (Sabbatical) year arrives every 7th year#The
Jubilee (
Yovel) year comes after 7 times 7 years#The
Counting of the Omer leading up to the Giving of the Torah is expressed as "7 times 7 weeks"
*The weekly
Torah portion is divided into seven
aliyahs, and seven men or boys over the age of 13 are called up for the reading of these aliyahs during
Shabbat morning services
*Seven blessings are recited under the
chuppah during a Jewish wedding ceremony
*A Jewish bride and groom are feted with seven days of festive meals after their wedding, known as
Sheva Berachot ("Seven Blessings")
*The number of
Ushpizzin (also known as the "Seven Shepherds") who visit the sukkah during the holiday of
Sukkot:
Abraham,
Isaac,
Jacob,
Joseph,
Moses,
Aaron, and
David*The number of nations God told the
Israelites they would displace when they entered the land of
Israel (Deut. 7:1): the Hittite, the Girgashite, the Amorite, the Canaanite, the Perizzite, the Hivite, and the Jebusite
*In
Breslov tradition, the seven orifices of the face (2
eyes, 2
nostrils, 2
ears, and the
mouth) are called "The Seven Candles"
* The number of
churches of Asia to which the Book of Revelation is addressed
* The number of
ayat in
surat
al-Fatiha* The number of
heavens in
Islamic tradition
* The number of
Earths in
Islamic tradition
* The numbers 7, 70, 70,000, etc. are used in Islamic traditions to denote an infinite or high number. In Arabic, 70, 70,000, etc. is used to mean infinite. This is because 1 is the smallest number, 2 is just after 1, 5 and 10 are exact, 4 and 6 are just before and after 5, and 9 is just before 10. This leaves 3, 7, and 8. 8 is closer to the end although it is larger. 8 is also an even number, so divisible by 2. Between 3 and 7, 3 is smaller so 7 is chosen to represent infinite.
* The number of
Seven Virtues: Chastity, Abstinence, Diligence, Liberality, Patience, Kindness, and Humility, and the corresponding
Seven Deadly Sins: lust, avarice, envy, pride, sloth, gluttony and wrath
* The seven terraces of Mount
Purgatory (one per deadly sin)
* The number of
sacraments in the
Roman Catholic faith
* The number of palms in an
Egyptian
Sacred Cubit* The number of heads of
the beast of the
Book of Revelation, and of some other monsters, like the
hydra* The minor symbol number of
yang from the Taoist
yin-yang* The number of times Cain will be avenged upon for the murder of his brother Abel
* The number of ranks in
Mithraism* The number seven is of particular significance within
Cherokee cosmology
*In
Khasi mythology, the seven divine women who were left behind on earth and became the ancestresses of all humankind
* The number of gateways traversed by
Inanna during her descent into the
underworld* The number of sleeping men in the Christian myth of the "
Seven Sleepers"
* The number of sages in
Hindu mythology. Their wives are the goddesses referred to as the "Seven Mothers"
*
The Magical Number Seven, Plus or Minus Two is the title of a 1956 paper by the cognitive psychologist George A. Miller which hypothesises that the effective channel capacity of human senses is equivalent to between 5 and 9 equally-weighted error-less choices.
*When asked to choose a number between 1 and 10, most people will choose 7. It is the most common number thought of off the top of one's head.
* The number of notes in the
musical scale* In music, the Roman numeral vii is the
subtonic (bVII) or
leading tone (VII)
scale degree,
chord, or
diatonic function, when distinguished V = major and v = minor.
* The number of completed, numbered symphonies of
Jean Sibelius and
Sergei Prokofiev* A pop music singer in
South Korea : 세븐 ;
SE7EN (singer) * A five-piece
teenybopper band from the late
1980s.
Albums
* A
2004 album by The Tea Party: see
Seven circles (Tea Party album.
* A
2003 album by
Atmosphere: see
Seven's Travels.
* A
2003 album by
Enrique Iglesias: see
7 (Enrique Iglesias album).
* A
2002 EP by
U2: see
7 (EP).
* A
2000 album by
S Club 7: see
7 (S Club 7 album).
* A
1997 album by
Zap Mama: see
7 (Zap Mama album).
* A
1996 album by
Apoptygma Berzerk: see
7 (Apoptygma Berzerk album).
* A
1992 album by
James: see
Seven (James album).
* A
1986 album by
George Strait: see
7 (George Strait album).
* A
1985 album by
David Meece: see
7 (David Meece album).
* A
1981 album by
Madness: see
7 (Madness album).
* A
1974 album by
Poco.
* A
1974 album by
Bob Seger: see
Seven (Bob Seger album).
* A
1991 album by
Mannheim Steamroller: see
Fresh Aire 7 * The album
Seventh Son of a Seventh Son by
Iron Maiden, based on a book with the same name written by
Orson Scott Card.
* The
1996 album
The Don Killuminati: The 7-Day Theory by
Tupac Shakur.
Songs
* The song "
Seven" by
David Bowie* The song "Seven" by
Sunny Day Real Estate* The song "Seven" by
Gackt* The song "Seven by
Necrophagist* The song "
7" by
Prince* The short instrumental piece "7" by
Moby* The song "
Seven Nation Army" by
The White Stripes* The song "
Seven Seas of Rhye" by
Queen* The song "Song Seven" by
Interpol* In
rugby league, the scrum-half/halfback
* In
rugby union, the openside flanker
* In
baseball, seven represents the
left fielder's position
* Retired jersey number of former baseball player
Mickey Mantle and former hockey player
Ted Lindsay.
*
Seven Cycles, a bicycle manufacturer
* Number of
John Elway, Hall of Fame QB of the
Denver Broncos.
* Number associated with
England National Team captain,
David Beckham.
* The
code for international direct dial phone calls to
Russia and
Kazakhstan* On most phones, the 7 key is associated with the letters
P,
R, and
S (there are a few phones that also put
Q on 7). On the
BlackBerry it is the key for
C and
V.
* The number of digits in an American
telephone number, excluding the
area code* The number of individual segments in one digit on a
digital clock or
calculator seven-segment display screen
* In all
Microsoft Office programs, the F7
function key calls up the spelling and grammar checker
* In
ASCII character set, the
bell character* A e-commerce company from
Cancun,
Mexico:
Seven Global.
* In an episode of
Seinfeld, the name
George Costanza desired to give his first-born (with
Susan Ross). In an attempt to prevent someone else from using the name, he later falsely claimed that he had promised this to the
widow of
Mickey Mantle, whose number was 7
* The name of one of the monsters in the cartoon television show
Seven Little Monsters* A character added to the cast of
Married... with Children who was quickly removed.
* 7 is the number of hearts needed by the gentlemen in "Buffy the Vampire Slayer" during the episode known to as "hush".
*In
Star Trek: Voyager,
Seven of Nine (also called Seven for short) is one of the crewmembers.
* The film
Se7en, directed in
1995 by
David Fincher.
* In the
Disney film
Herbie Goes to Monte Carlo (
1977), the car number of
Giselle, the
Lancia Scorpion with whom
Herbie falls in love.
*
James Bond's agent secret number is 007.
*Seven candles are lit in the
kinara during the
African-American celebration of
Kwanzaa, which is a seven-day holiday
* It is traditionally thought that there are seven continents on Earth.
* Seven is the smallest positive integer requiring more than one syllable in English.
* There are seven musicians in a
septet and seven babies born in a set of
septuplets. The most famous set of septuplets are the
McCaughey Septuplets, who were born in
1997.
* The
British fifty-pence and
twenty-pence coins are heptagons, with the sides curved to give them a
constant diameter.
* Many cities are claimed to be constructed amidst seven hills; see
Seven hills of Rome and
List of cities claimed to have been built on seven hills.
*
Serial sevens are used as a diagnostic test in medicine.
*In
linguistics, the "7" is sometimes used to represent a
glottal stop, as a substitute for .
* In
Fist of the North Star (
Hokuto no Ken), the main character,
Kenshiro, is also known as "the man with seven wounds" for the seven scars on his body in the shape of the
Big Dipper.
* The
Harry Potter series has several references to the number seven.
Seven is also:
* The largest number of sticks (or other cylindrical objects) that can be tied into a bundle such that the shape of the bundle remains fixed. This may have led to the number being viewed with mystical significance by ancient man.
* The number of
openings into the human
head (
mouth, two
eyes, two
ears, two
nostrils).
* The number of
spheres in the
Ptolemaic system* In
Astrology,
Libra is the 7th
astrological sign of the
Zodiac.
* The traditional number of
Wonders of the Ancient World.
* Viewed as a
lucky number in both
Japanese Culture and many Western cultures.
* The number of
days in a
week. Whether
Saturday or
Sunday is the seventh day varies across cultures.
* The number of the
ages of man into which William Shakespeare divided a lifetime
* The figurative number of
seas* The number of colors of the
rainbow (the
asteroid 7 Iris is named after the rainbow goddess
Iris)
* The number of basic principles of the
bushido* The number of points on a
sheriff's
star* The average number of digits that can be stored in
short-term memory* In
Galician folklore, a
seventh son will be a
werewolf. In other folklores, after six daughters, the seventh child is to be a son and a werewolf. In other European folklores, the seventh son of a seventh son will be a
vampire.
* When rolling two standard six-sided
dice, seven is the number most likely to occur.
* Seven is the sum of any two opposite sides on a standard six-sided die
* The number of dwarves in the movie
Snow White* The number of rings given to the Dwarf Lords in J.R.R. Tolkien's
The Lord of the Rings* The
Heptarchy, from the (
Greek for
seven realm, is the name applied by historians to the period (
500-
850 AD) in
English history after the
Anglo-Saxon conquest of
England, derived from the seven kingdoms of
Northumbria,
Mercia,
East Anglia,
Essex,
Kent,
Sussex, and
Wessex, which eventually merged to become the
Kingdom of England during the early
10th century.
*
September was the seventh month in the ancient
Roman calendar, as its name indicates. After
the reform that led to the current order, the seventh month is July.
*
Septidi was the seventh day of the
decade in the
French Revolutionary Calendar* The traditional count of
Basque provinces as expressed in the slogan
Zazpiak Bat* The
Seven Sages of Greece: Solon, Chilon, Thales, Bias, Cleobulus, Pittacus and Periander.
*
Cibola was the legendary Seven Cities of Gold the Spanish thought existed.
*In tarot, card No. 7 is "the Chariot"
Names and titles
Seven or
7 is all or part of a number of names and titles of people, artworks or organizations, including:
*
Sevens, a card game
* An agency of photojournalists founded by seven photographers
* Canadian fashion photographer Sev Seven
* Musician/actor
Andre Benjamin's and singer
Erykah Badu's son, Seven.
* The stage name of musician
Keith Volpone*
SE7EN (singer), a Korean R&B/hip-hop singer
* Part of the names of:
**
Aleksis Kivi's "
Seven Brothers", the most famous book of Finnish literature
**
Seven Pillars of Wisdom, a book written by
T. E. Lawrence**
The Secret Seven, name of children adventure book by
Enid Blyton** The book
Seven Years in Tibet**
Kurosawa's film
The Seven Samurai, that inspired the
1960 movie with
Steve McQueen The Magnificent Seven and its own sequels
** Several groupings called the
Seven Sisters**The Anime
Eureka Seven** The Seven Virgins:
*** The
Seven Virgins mountain range in
Sri Lanka, which was the scene of an
air disaster on
4 December 1974, involving a DC-8 Series 55F passenger jetliner operated by the charter company
Martinair which left 191 dead.
*** the
Saptha Kanniyar were seven faithful devotees of
Siva, who give birth to seven boys, in
Hindu mythology.
*** An anonymous
17th Century carol,
The Seven Virgins.
** Seven Sisters, a
1998 song album by pop singer
Meja**
Seven of Nine, a crewmember in the
Star Trek universe
** The
World Sevens Series in
Rugby Union, including the
Hong Kong Sevens**
the sport itself** The
Seven Network of
Australia**
The Seven Habits of Highly Effective People, a book by
Stephen Covey** The metal band
Avenged Sevenfold, also known as A7X.
**
Seven Nation Army, a single by the
White Stripes*
007,
codename for
James Bond, a fictional secret
spy agent
* In the
InuYasha series, the
Shichinintai are, as their name says, a band of seven mercenaries.
* In the
Fushigi Yuugi series, the four beast gods each have seven warriors. The Genbu Seven, the Byakko Seven, the Seiryuu Seven, and the Suzaku Seven.
* In the
One Piece series, the
Seven Warlords of the Sea (known in Japan as the Shichibukai, or Seven Arm Seas), are seven powerful pirates.
* The number of individual personalities serving
Harman Smith as part of the group of assassins called the
Killer7, hence the title of the game.
* In the catalan culture, 7 is present in a lot of popular stories like "Les set cabretes i el llop".
A.D. 7,
7 B.C.,
1907,
2007, etc.
*
Septenary (numeral system)*
Septenary (Theosophy)*
Seven climeszh-yue:7
