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# 7 (number)

''
7
Cardinal 7
seven
Ordinal 7th
seventh
Numeral system septenary
Factorization prime
Divisors 1, 7
Roman numeral VII
Roman numeral (Unicode) Ⅶ, ⅶ
Amharic
Indian ٧
Bengali
Chinese numeral 七，柒
Devanāgarī
Hebrew ז (Zayin)
Khmer
Thai
prefixes hepta-/hept- (from Greek) septua- (from Latin)
Binary 111
Octal 7
Duodecimal 7

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

## In mathematics

### 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. 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, sometimes with 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.
• Seven is the number of holes in the heads of most mammals.

## In the classical world

In classical antiquity:

## 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—()), 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.

### 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.
• Circle Seven Koran, the holy scripture of the Moorish Science Temple of America

## 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 literature

• In The Lost Years of Merlin series, a book is titled "The Seven Songs of Merlin"
• In the Harry Potter series of novels by J. K. Rowling, seven is said to be the most powerfully magical number. There are a number of references to seven in Harry Potter: There are a total of seven books in the series; Ginny Weasley is the seventh child and only daughter of the Weasley family; Harry Potter was born in July, the seventh month of the year; Wizarding students must complete seven years of school at Hogwarts; Lord Voldemort splits his soul into seven parts which he believes ensures his immortality. Seven is also the number on the back of Harry Potter's Quidditch robes (Prisoner of Azkaban movie). In Quidditch each team consists of seven players. Chapter four of Book 7 is titled "The Seven Potters".
• In The Two Towers, the second volume of J. R. R. Tolkien's The Lord of the Rings, the following poem appears: "Tall ships and tall kings/Three times three/What brought they from the foundered land/Over the flowing sea?/Seven stars and seven stones/And one white tree." The "foundered land" is Númenor, and the "Seven Stars" are unknown, but they may refer to a constellation, the Sickle of the Valar. The Seven Stones are the palantíri, the seeing-stones. Also in The Lord of the Rings, the Dwarves were given seven rings.
• In The Silmarillion, also a Tolkien work, there are seven Lords of the Valar, and seven Ladies of the Valar; Fëanor, a central character, has seven sons: Maedhros, Maglor, Celegorm, Curufin, Caranthir, Amrod, and Amras.
• 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 child with special powers of healing and clairvoyant seeing.
• 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.
• 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 a children's adventure book by Enid Blyton.
• The book Seven Years in Tibet.
• The anime Eureka Seven.
• The character 7 (Nana) and the organisation Septimal Moon in Loveless (manga).
• The Seven Habits of Highly Effective People, a book by Stephen Covey.
• Team 7 consists of the main characters in Naruto: Naruto Uzumaki, Sasuke Uchiha, Kakashi Hatake, and Sakura Haruno.
• In the One Piece series, the Shichibukai (literally, "Seven Military Seas", known in the English versions as the "Seven Warlords of the Sea") are seven powerful pirates who work for the government.
• In the InuYasha series, the Shichinintai are, as their name says, a band of seven mercenaries.
• In the Nana series, there are many recurrent instances of the number seven ("nana" is the Japanese numeral for the English "seven"), including the name of both main characters.
• In George R. R. Martin's A Song of Ice and Fire, seven gods, the Mother, the Father, the Warrior, the Crone, the Smith, the Maiden, and the Stranger, are worshipped in the land of Westeros, which is made up of seven former kingdoms and often called the Seven Kingdoms. The Seven are the primary deities of Westeros.
• In Neil Gaiman's Sandman series, there are 7 Endless: Destiny, Death, Dream, Destruction, Despair, Desire and Delirium.
• The Saga of Seven Suns, a series of seven novels by Kevin J. Anderson.
• In W.E.B. Du Bois's book The Souls of Black Folk, he refers to “the Negro” as “the seventh son.”
• In Septimus Heap Book one Magyk. Septimus Is the seventh son of a seventh son, 7 is believed to be the most magykal number.
• In the first of the three Deltora Quest series of books by Emily Rodda, the protagonist must collect the seven gems of the fabled Belt of Deltora: topaz, ruby, opal, lapis lazuli, emerald, amethyst, and diamond. Each of the seven gems are guarded by one of seven guardians located in one of the seven locations around Deltora: The Forests of Silence, Lake of Tears, City of the Rats, The Shifting Sands, Dread Mountain, Maze of the Beast, and Valley of the Lost.
• A book is currently being written about 7 by Jacqueline Leo and Edward Burger
• The Seven Rings of the Vongola Family in Katekyo Hitman Reborn: Sky, Storm, Rain, Sun, Thunder, Mist, and Cloud.

## In video games

• 7 is a number used many times by Bungie Studios in their Halo series and Marathon trilogy. 7 appears in a variety of different contexts, from the stories of the games to the raw game coding.
• 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 Kingdom Hearts there are seven Princesses of Heart (Snow White, Cinderella, Alice, Aurora, Belle, Jasmine, and Kairi (the only original character among them)). Seven (VII) is also the number of the character Saïx, a member of the antagonists Organisation XIII from Kingdom Hearts II.
• In The Legend of Zelda: Ocarina of Time, the main quest involves awakening the seven sages of seven elements to banish evil from the land of Hyrule.
• The number of Koopalings on Super Mario Bros. 3 and Super Mario World. It is also the number of worlds on Super Mario World, not counting the Star World or the Special course; and it is also the number of worlds on Super Mario Bros. 2.
• The 7 is a group of deadly mercenaries that kidnap the protagonist's family in the video game Kane & Lynch: Dead Men.
• In the Ace Attorney Series, 7 is a recurring number. For example: There is a 7 year age gap between the main character and his assistant, there is a 7 year gap between the plots of Ace Attorney 3 and 4, the Chief of police, Gant's keycard number is 7777777.
• Nana (One of two Japanese readings for "seven" and also a common feminine name) is one of the supporting characters in
• In Sega's Sonic the Hedgehog video game franchise, there are seven Chaos Emeralds.

## In other fields

• The Kulin people of Australia living near the Dandenong Ranges traditionally have seven seasons. Some of the Native Americans of Montana also have seven seasons: chinook season, muddy spring, green summer, gold summer (or dry summer), 'Indian' Summer, late fall, and cold winter.
• The United States declared Independence in the 7th month of 1776.
• Lotto Super 7, a Canadian-lottery game

Seven is also: