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7
0 1 2 3 4 5 6 7 8 9 → List of numbers — Integers 0 10 20 30 40 50 60 70 80 90 →
Cardinal	7 seven
Ordinal	7th seventh
Numeral system	septenary
Factorization	prime
Divisors	1, 7
Roman numeral	VII
Roman numeral (Unicode)	Ⅶ, ⅶ
Amharic	፯
Indian	٧
Bengali	৭
Chinese numeral	七，柒
Devanāgarī	७
Hebrew	ז (Zayin)
Khmer	៧
Thai	๗
prefixes	hepta-/hept- (from Greek) septua- (from Latin)
Binary	111
Octal	7
Duodecimal	7
Hexadecimal	7

7 (seven) is the natural number following 6 and preceding 8.

Contents 1 In mathematics 1.1 In numeral systems 1.2 List of basic calculations 2 Evolution of the glyph 3 In science 3.1 Chemistry 3.2 Astronomy 4 In technology 5 In the classical world 6 In religion 6.1 Judaism 6.2 Christianity 6.3 Hinduism 6.4 Islam 6.5 Bahá'í 6.6 Others 7 In mythology 8 In psychology 9 In music 10 In television 11 In film 12 In literature 13 In video games 14 In sports 15 In other fields 15.1 Names and titles 16 Notes 17 See also 18 References 19 External links

[ In mathematics

• Seven is the fourth prime number. It is not only a Mersenne prime (since 2³ − 1 = 7) but also a double Mersenne prime since it is itself the exponent for another Mersenne prime (127). It is also a Newman-Shanks-Williams prime, a Woodall prime, a factorial prime, a lucky prime, and a safe prime.

• Seven is the only number less than 15 which cannot be represented as the sum of the squares of three integers.

• Seven is the aliquot sum of one number, the cubic number 8 and is the base of the 7-aliquot tree.

• n = 7 is the first natural number for which the next statement does not hold: "Two nilpotent endomorphisms from Cⁿ with the same minimal polynomial and the same rank are similar."

• 7 is the only dimension, besides the familiar 3, in which a vector cross product can be defined.

• 999,999 divided by 7 is exactly 142,857. Therefore, when a vulgar fraction with 7 in the denominator is converted to a decimal expansion, the result has the same six-digit repeating sequence after the decimal point, but the sequence can start with any of those six digits.^[1] For example, 1/7 = 0.142 857 142.... and 2/7 = 0.285 714 285...

• A seven-sided shape 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.

• There are seven fundamental types of catastrophes.

• When rolling two standard six-sided dice, it is the sum of any two opposite sides on a standard six-sided die. It has a 6 in 36 (or 1/6th) probability of being rolled (1–6, 6–1, 2–5, 5–2, 3–4, or 4–3), the greatest of any number.

[ In numeral systems

Base	Numeral system
2	binary	111
3	ternary	21
4	quaternary	13
5	quinary	12
6	senary	11
7	septenary	10
over 7 (octal, decimal, etc)		7

In quaternary, 7 is the smallest prime with a composite sum of digits.

In the English language, 7 is the only 2-syllable natural, positive 1-digit number 7 is the 6th number of the alphabet

[ List of basic calculations

Multiplication	1	2	3	4	5	6	7	8	9	10		11	12	13	14	15	16	17	18	19	20		21	22	23	24	25		50	100	1000
7 × x	7	14	21	28	35	42	49	56	63	70		77	84	91	98	105	112	119	126	133	140		147	154	161	168	175		350	700	7000

Division	1	2	3	4	5	6	7	8	9	10
	11	12	13	14	15
7 ÷ x	7	3.5	2.3	1.75	1.4	1.16	1	0.875	0.7	0.7
	0.63	0.583	0.538461	0.5	0.46
x ÷ 7	0.142857	0.285714	0.428571	0.571428	0.714285	0.857142	1	1.142857	1.285714	1.428571
	1.571428	1.714285	1.857142	2	2.142857

Exponentiation	1	2	3	4	5	6	7	8	9	10		11	12	13
7x	7	49	343	2401	16807	117649	823543	5764801	40353607	282475249		1977326743	13841287201	96889010407
x7	1	128	2187	16384	78125	279936	823543	2097152	4782969	10000000		19487171	35831808	62748517

Radix	1	5	10	15	20	25	30	40	50	60	70	80	90	100
	110	120	130	140	150	200	250	500	1000	10000	100000	1000000
x7	1	5	137	217	267	347	427	557	1017	1147	1307	1437	1567	2027
	2157	2317	2447	2607	3037	4047	5057	13137	26267	411047	5643557	113333117

[ Evolution of the glyph

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, so they were also concerned with making their 7 more different. For the Khmer this often involved adding a horizontal line above the glyph.^[2] 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.

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 in Japan and Korea 7 is written as ① in the illustration to the right.

While the shape of the 7 character has an ascender in most modern typefaces, in typefaces with text figures the character usually has a descender, as, for example, in .

Some people, especially in Europe and Latin America, write 7 with a line in the middle and make the top line crooked. The line through the middle is useful to clearly differentiate the character from the number one, as these can appear similar when written in certain styles of handwriting.

[ In science

• Roy G. Biv = red, orange, yellow, green, blue, indigo, and violet were originally named as the seven colors of the rainbow, though blue and indigo are considered by some to be the same color.
• The number of spots on a common ladybug.
• The seven days of the week.
• With very few exceptions, all mammals' necks have seven bones.

[ Chemistry

• A neutral pH value between acidity and alkalinity.
• The atomic number of nitrogen.
• The number of carbon atoms in heptane, a hydrocarbon.
• The number of periods, or horizontal rows of elements, on the periodic table.

[ Astronomy

• The number of stellar 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 number of daughters of Atlas in the Pleiades (also called the "seven sisters").
• The number of saints appearing in a constellation called "Saptharishi Mandalam" in Indian astronomy.
• The number of stars in the constellation of The Big Dipper.
• 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 1,280.1 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 1,586.6 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).

[ In technology

• The code for international direct dial phone calls to Russia and Kazakhstan.
• There are seven classes of plastics used in packaging applications.
• The resin identification code used in recycling to identify "other" plastics such as polycarbonate
• The number of digits in an American or Canadian telephone number, excluding the area code.
• In Microsoft's Rich Text Format specification, seven and all numbers congruent to it modulo 256 refer to variants of the German language.
• Windows 7, the upcoming Microsoft operating system sometimes referred to as just "7".
• In the ASCII character set, the bell character.
• There are Seven Tools of Quality.

• There are seven layers in the OSI model.
• There are seven logic gates. NOT, AND, OR, NAND, XOR, NOR, XNOR
• The seven-segment display, is an electronic device that uses seven individual segments to create one digit; it is used in display devices like digital clocks and some basic calculator screens, amongst others.

[ In the classical world

In classical antiquity:

• Seven against Thebes
• Seven Emperors (and period; Rome, history)
  • Julius Caesar, Augustus, Galba, Hadrian, Nerva, Sallust, Vespasian
• Seven hills of Rome
• Seven Liberal Arts
• Seven Sages
• Seven Wonders of the ancient world

[ In religion

[ Judaism

• 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 seventh day (Shabbat). - Genesis 2:3. "Wisdom has built her house, she has hewn out her seven pillars." - Proverbs of Solomon son of David King of Israel 9:1
  • A seven-day purification period is required for one who has become tamei to become tahor.
  • The Shmita (Sabbatical) year arrives every seventh 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."
  • There are 7 days of Passover and Sukkot when celebrated in Israel.
  • Shiv`a (another pronunciation of the Hebrew word for 7—(Hebrew: שבעה ; "seven")), is the number of days of mourning. Hence, one sits Shiva. As in Shiva (Judaism)
• 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 menorah (Hebrew: מנורה), is a seven branched candelabrum lit by olive oil in the Tabernacle and the Temple in Jerusalem. The menorah is one of the oldest symbols of the Jewish people. It is said to symbolize the burning bush as seen by Moses on Mount Sinai (Exodus 25).
• The number of times Cain will be avenged by God if he is murdered (Gen 4:15).
• The Israelites circled Jericho for 7 days and then the wall tumbled down.
• Yahweh or Jehovah is the divine name, whose letters' placed alphabetically equal 70, a product of the divine number 7.

[ Christianity

• The Seven Sacraments in the Catholic faith (though some traditions assign a different number).
• The Seven churches of Asia to which the "Book of Revelation" is addressed.
• The Seven Joys of the Virgin Mary, of Roman Catholic, Anglican, and other traditions.
• The Seven Sorrows of the Virgin Mary, of Roman Catholic, Anglican, and other traditions.
• The Seven Corporal Acts of Mercy of Roman Catholic, Anglican, and other traditions.
• The Seven Spiritual Acts of Mercy of Roman Catholic, Anglican, and other traditions.
• The Seven last words (or seven last sayings) of Jesus on the cross.
• The Seven Virtues: chastity, temperance, charity, diligence, kindness, patience, and humility
• The Seven deadly sins: lust, gluttony, greed, sloth, wrath, envy, and pride.
• The seven terraces of Mount Purgatory (one per deadly sin).
• In the genealogy in the Gospel of Luke, Jesus is 77th in a direct line.
• The number of heads of the three beasts (7 \times; 10 \times; 7 + 7 × 10 × 10 + 7 × 10 = 1260) of the Book of Revelation, and of some other monsters, like the hydra and the number of seals.
• In the New Testament, the Gospel of Matthew 18:21, Jesus says to Peter to forgive seventy times seven times.^[3]
• There are seven suicides mentioned in the Bible (OT and NT) ^[4]

[ Hinduism

• The Sanskrit word 'sapta' refers to number seven.
• The Indian Music has 'sapta swaras', means seven octats (sa re ga ma pa dha ni), which are basics of music, using which hundreds of Ragas are composed.
• Celestial group of seven stars are named as 'Sapta Rishi' based on the seven great saints.
• Seven Promises, Seven Rounds in Hindu Wedding and Seven Reincarnation
• As per Hindu mythology, there are seven worlds in the universe, seven seas in the world and seven Rishies (seven gurus) called sapta rishis.
• seven hills at tirumala also known as ezhu malaiyan means Sevenhills god

[ Islam

• The number of ayat in surat al-Fatiha.
• The number of heavens in Islamic tradition.
• The number of Earths in Islamic tradition.
• The number of circumambulations (Tawaf) that are made around the Kaaba
• The number of walks between Al-Safa and Al-Marwah mountains -that is travelling back and forth- seven times during the ritual pilgrimages of Hajj and Umrah.
• The number of fires in hell. i.e the 7 fires of hell.
• The number of doors to heaven and hell is also seven.

[ Bahá'í

• The mystical text "The Seven Valleys", by the Prophet-Founder Bahá'u'lláh, relates the journey of the soul through the seven "valleys" of Search, Love, Knowledge, Unity, Contentment, Wonderment, and finally True Poverty and Absolute Nothingness.

[ Others

• The number of Archangels according to some systems.
• The minor symbol number of yang from the Taoist yin-yang.
• The number of palms in an Egyptian Sacred Cubit.
• The number of ranks in Mithraism.
• The number seven is of particular significance within Cherokee cosmology.
• In Buddhism, Buddha walked 7 steps at his birth.

[ In mythology

• 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 Seven Sages in Sumerian mythology and various other mythologies.
• The number of sages in Hindu mythology; their wives are the goddesses referred to as the "Seven Mothers."
• The number of main islands of mythological Atlantis.
• In Guaraní mythology, the number of prominent legendary monsters.
• Seven Lucky Gods exist in Japanese mythology.
• In Irish Mythology, the epic hero Cúchulainn is associated with the number 7. He has 7 fingers on each hand, 7 toes on each foot, and 7 pupils in each eye. In the Irish epic Táin Bó Cúailnge, Cúchulainn is 7 years old when he receives his first weapons and defeats the armies of the Ulaidh. and his son Connla is 7 years old when he is slain by Cúchulainn in "The Death of Aife's Only Son".
• In British Folk lore, every 7 years the Fairy Queen pays a tithe to Hell (or possibly Hel) in the tale of Tam Lin.
• In the British Folk tale of Thomas the Rhymer, he went to live in the faerie kingdom for 7 years.
• The 7th glyph of the Mayan Calendar is Blue Hand, it represents the days in creation and is associated with creative perfection. This is the glyph of the last day of their calendar that ends on December 21st 2012.
• The seven branched sword in Korean mythology.

[ In psychology

• The Magical Number Seven, Plus or Minus Two is a 1956 paper by cognitive psychologist George A. Miller, who found a correlation between various human cognitive capacity limits within the range 7 ± 2.

[ In music

• 7 is the pseudonym of American musician Mick Thomson, when performing with Slipknot
• A famous dance group from Kercova(Macedonia)- Sevens group
• The number of notes in the traditional Western Major Scale
• The original diameter in inches of the 45rpm format gramophone record.
• In music, the Roman numeral vii is the leading tone (vii°) or subtonic (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: SE7EN (singer).
• There are seven musicians in a septet or a septuor.
• The stage name of musician Keith Volpone.
• The name of Jurassic 5 member Mark 7even.
• 7 is an album by Apoptygma Berzerk.
• 7 is a song by Prince from his album Love Symbol released in 1992.
• 7 Shades of Black is a song on the Smashing Pumpkins album Zeitgeist, which made its release in 2007.
• A 2003 Atmosphere album is titled Seven's Travels, after an early alias of the group's MC, Slug
• Love Is the Seventh Wave by Sting on his first solo album, Dream of the Blue Turtles.
• Iron Maiden's second #1 album was entitled Seventh son of a Seventh son
• Former Bone Thugs N Harmony member Bizzy Bone's record label is named 7th Sign Records, also called the 7th Sign Regime
• The albums: Keeper of the Seven Keys Part 1, Keeper of the Seven Keys Part 2 and Keeper of the Seven Keys - The Legacy, by Helloween.
• The song: The Bells of the 7 Hells, by Helloween on the Album Gambling With the Devil.
• The songs: Seven and Seven Days of the Week (I Never Go to Work), by They Might Be Giants on the Album Here Come the 123s.
• The name of the first album by British indie rock and roll band Moral Soul
• The song Seventy Times Seven by Brand New.
• The album 7 by S Club 7
• The song Seventh Heaven by l'Arc En Ciel, also by Perfume
• The album 7 by polish rapper and freestyler O.S.T.R.

[ In television

• The name of one of thee monstSource: this wikipedia article, under GFDL.
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