7 (number): Wikis

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Encyclopedia

7
Cardinal 7
seven
Ordinal 7th
seventh
Numeral system septenary
Factorization prime
Divisors 1, 7
Roman numeral VII
Roman numeral (Unicode) Ⅶ, ⅶ
Amharic
Arabic ٧,7
Persian ٧ - هفت
Bengali
Chinese numeral 七，柒
Devanāgarī
Tamil
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.

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 vertically inverted. 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 because, 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 .

Most people in Europe, Latin America, and New England, write 7 with a line in the middle ("7"), 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. This glyph is used in official handwriting rules for primary school in Russia.[3]

In science

Chemistry

Heptane is an alkane with 7 carbon atoms per molecule

In religion

Christianity

Seven Days of Creation - 1765 book

The number seven (7) in the seven days of Creation is typological and the number seven appears commonly elsewhere in the Bible. These include:

• Seven days of Creation (Genesis 1). God rested on and sanctified the seventh day (Sabbath)
• Seven years of plenty and seven years of famine in Pharaoh's dream (Genesis 41)
• Seven days of the feast of Passover (Exodus 13:3-10)
• Seven day week and the pattern concerning distribution and use of manna (Exodus 16)
• Seven year cycle around the years of Jubilee (Leviticus 25)
• The fall of the walls of Jericho on the seventh day after marching around the city seven times(Joshua 6)
• Seven things that are detestable to the LORD (Proverbs 6:16-19)
• Seven Pillars of the House of Wisdom (Proverbs 9:1)
• Seven loaves multiplied into seven baskets of surplus (Matthew 15:32-37)
• The Seven last words (or seven last sayings) of Jesus on the cross.
• Seven men of honest report, full of the Holy Ghost and wisdom (Acts 6:3)
• Seven Spirits of God are mentioned in the Book of Revelation.
• Seven churches of Asia to which the "Book of Revelation" is addressed.
• Seven churches, seven stars, seven seals, seven last plagues, seven vials or bowls, seven thunders in the Revelation, the last book of the Bible.

Other sevens in Christian knowledge and practice include:

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
• According to Hinduism, 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
• There are 7 Chakras in meditation.

Islam

• The number of ayat in surat al-Fatiha.
• The number of heavens in Islamic tradition.
• The number of levels of Earth 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 hell is also seven.
• In Verse 12:46 (see Islamic view of Joseph) of the Quran, Joseph (Yusef) is asked to interpret the King's dream where seven fat cows were dreamt to have been devoured by seven skinny cows and seven green spikes, and others shrivelled.
• It is widely accepted that Surah Al Kahf (Surah 18, verse 9-26) narrates the story of Seven Sleepers who travelled in time by sleeping in a cave for three hundred solar years and nine lunar years, which is similar to the christian myth of the same name.

Judaism

The Menorah is a 7-branched candelabrum
• 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 Jewish men (or boys over the age of 13 who are considered men; Bar Mitzvah) 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.

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 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.
• In Buddhism, Buddha walked 7 steps at his birth.
• Circle Seven Koran, the holy scripture of the Moorish Science Temple of America
• In Spanish and other Romance Languages, cats are said to have 7 lives as opposed to English, where cats are said to have 9 lives.
• In Iran cats are also said to have 7 lives.[8]
• In Wiccan spirituality the number seven is said to hold a lot of divinity. It is known for being a very sound number and associates with many things.
• The Seven Lucky Gods refer to the seven gods of good fortune in Japanese 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[citation needed] 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.
• 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 21, 2012.
• The seven branched sword in Korean mythology.

In video games

• In Sega's Sonic the Hedgehog video game franchise, there are often seven Chaos Emeralds
• 7 is a number used many times by Ensemble Studios and 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. Further, the number of years separating the child and adult stages of the game is seven.
• Another Zelda title, The Legend of Zelda: A Link to the Past, involves a similar quest in which the player must rescue seven maidens before confronting Ganon.
• 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.
• In Paper Mario: The Thousand-Year Door, Mario's goal is to collect the seven Crystal Stars scattered across the world.
• 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 Mega Man X: Command Mission.
• In Super Mario RPG: Legend of the Seven Stars, Mario and his gang need to collect seven stars to repair the Star Road.
• In The World Ends with You, one of the antagonists is a musician called "777".
• In Final Fantasy VII If anyone in your party's HP reaches to 7777, they will go berserk and strike the opponent a number of times at a damage rate of 7777. This is called the Lucky 7's. After the battle, however, the character's HP will be reduced to 1 to prevent this state from rolling over to another battle.
• In Valkyria Chronicles, you control Squad 7 of the militia force.

In other fields

• The seven days of the week
• 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 that will have its final drawing September 18, 2009

Seven is also:

Names and titles

• Sevens, a card game.
• The Seven Virgins mountain range in Sri Lanka, which was the scene of an air disaster on December 4, 1974, involving a DC-8 Series 55F passenger jetliner operated by the charter company Martinair, which left 191 dead.
• 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.
• 7UP is the name of a popular soft drink.
• 7-Eleven is the trading name of a chain of convenience stores based in the U.S.
• Seven Jeans, also known as Seven '7' for all Mankind, a brand of designer jeans.
• 7 (New York City Subway service), a service of the New York City Subway
• The Ultra Series has two heroes with "Seven" in their name: Ultra Seven and Ultra Seven-21.
• The circle 7 logo used by numerous ABC network O&O stations in the United States.
• The Lotus Seven, a kit car produced by Lotus
• The Solid Seven is the nickname for the 7 sophomores on the Lafayette College basketball team that run things around campus

Notes

1. ^ Bryan Bunch, The Kingdom of Infinite Number. New York: W. H. Freeman & Company (2000): 82
2. ^ Georges Ifrah, The Universal History of Numbers: From Prehistory to the Invention of the Computer transl. David Bellos et al. London: The Harvill Press (1998): 395, Fig. 24.67
3. ^ "Education writing numerals in grade 1."(Russian)
4. ^ "SI brochure, The seven SI base units". Retrieved 2009-09-11.
5. ^ "SI brochure, SI derived units". Retrieved 2009-09-11.
6. ^ 21Then Peter came to Jesus and asked, 'Lord, how many times shall I forgive my brother when he sins against me? Up to seven times?' 22Jesus answered, 'I tell you, not seven times, but seventy times seven.'.
7. ^ Bible.org: Sermon Illustrations
8. ^ Encyclopedia Britannica "Number Symbolism"

References

• Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group (1987): 70–71

Simple English

Simple English Wiktionary has the word meaning for:

The number seven is a natural number that comes after six and before eight.

Math

In math, the number seven is an odd number and a prime number.

In the world

[[File:|thumb|right|200px|The 7 colors of the rainbow.]]

• There are seven colors in the rainbow.