Information about 7 (number)

''
0 1 2 3 4 5 6 7 8 9
Cardinal7
seven
Ordinal7th
seventh
Numeral systemseptenary
Factorizationprime
Divisors1, 7
Roman numeralVII
Roman numeral (Unicode)Ⅶ, ?
Arabic٧
Bengali
Chinese numeral?
Devanāgarī
Hebrewז (Zayin)
Khmer?
prefixeshepta-/hept-
Binary00000111
Octal7
Duodecimal7
Hexadecimal7
Enlarge picture
Seven Days of Creation - 1765 book, title page


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

In mathematics

# 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 simple, once the number n is rewritten in the form:
:n = 10a + b
Where:
: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)


A second divisibility rule was formulated in 2006 in India, by Himanish Ganjoo, a Class 8 student in St. Columba's School Delhi:
# Remove the last two digits
# Divide the remaining number by 7
# Multiply the remainder by 2
# Add the product to the last two digits
# If the sum is divisible by 7, the number is also divisible


On March 25, 2007, Ganjoo formulated another variant form of this test, now separating the last 3 digits (in step 1), and multiplying the remainder by 6 (step 3), and then adding the sum to the last 3 digits (originally separated).

For example, 1568 is divisible by 7,
# 15/7 Remainder = 1
# Product 1*2 = 2
# 68 + 2 = 70 (which is divisible by 7)


Hence, 1568 is divisible by 7

In numeral systems

Base Numeral system
2binary111
3ternary21
4quaternary13
5quinary12
6senary11
7septenary10
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

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
7142128354249566370778491981051121191261331401471541611681753507007000


Division 1 2 3 4 5 6 7 8 9 10
11 12 13 14 15
73.51.751.410.8750.7
0.5
1
2


Exponentiation 1 2 3 4 5 6 7 8 9 10 11 12 13
74934324011680711764982354357648014035360728247524919773267431384128720196889010407
1128218716384781252799368235432097152478296910000000194871713583180862748517


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
15

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.[1] 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 & 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 .

In science

  • The number of spots on a common ladybug.
  • With very few exceptions, all mammals' necks have seven bones.
  • ROY G. BIV = red, orange, yellow, green, blue, indigo, and violet are the 7 colours of the rainbow.

Chemistry

Astronomy

In technology

In the classical world

In classical antiquity:

In religion

  • In 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 (Sabbath).
  • A seven-day purification period is required for one who has become tamei to become tahor.
  • The Shemittah (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."
  • 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 Sabbath morning services.
  • Seven blessings are recited under the chuppah during a Jewish wedding ceremony.
  • David was the eighth son of Jesse.
  • 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).
  • On the 7th day of the 7th month of 1947, European Jews began the boarding the ship Exodus in France to return to Israel.
  • In Christianity:
  • Yahweh or Jehovah is the divine name, whose letters' places alphabetically equal 70, a product of the divine number 7.
  • The number of churches of Asia to which the "Book of Revelation" is addressed.
  • The number of the Seven Virtues: Chastity, Moderation, Liberality, Charity, Meekness, Zeal, and Humility, corresponding to the seven deadly sins.
  • Jesus told Peter that he should forgive someone who sinned against him 70 times 7 times.
  • The seven terraces of Mount Purgatory (one per deadly sin).
  • The number of sacraments in the Roman Catholic faith.
  • The number of heads of the three beasts 7*10*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.[2]
    • * The number of times Cain will be avenged by God if he is murdered (Gen 4:15).
    • In Roman Catholicism, and some reformed traditions, the Blessed Virgin Mary has Seven Joys: The Incarnation, the Visitation, the Nativity, the Visit of the Magi, the Finding of Jesus in the Temple of Jerusalem, the Resurrection of Christ, and The Assumption of Mary into Heaven.
    • In Roman Catholicism, and some reformed traditions, the Blessed Virgin Mary has Seven Sorrows: The Prophecy of Simeon, the Flight into Egypt, the Three Day Loss of the Christ Child in the Temple of Jerusalem, the Carrying of the Cross, the Crucifixion of Christ, the Pieta, and the Closing of the Holy Sepulchre.
    • In the genealogy in the Gospel of Luke, Jesus is 77th in a direct line.
    • The Isrealites circled Jericho for 7 days and then the wall tumbled down.
    • In 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 {Al-Safa and Al-Marwah) that is travelling back and forth seven times during the ritual pilgrimages of Hajj and Umrah.
    • In Eternalism:
    • The number of deities
    • The years Godzimir was exiled to Turin, in Savoy
    • 1/7 of each of the Deities powers was taken to create the Eternal
    • There are seven verses in each of the Septrains of the Prognostications of Godzimir and Invomandus
    • Seven universe in each phase toward Edication
    • 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 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.
    • The Month 'September' is evolved from the word 'septa' meaning seven. September was earlier seventh month before July and August were added to the calendar. Also the subsequent months names are derived from Sanskrit names 'Ashta' and 'Nava' meaning eight and nine which are now called October and November.
    • 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.

    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 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 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.

    In psychology

    In music

    In television

    • The name of one of the monsters in the cartoon television show Seven Little Monsters.
    • Seven, an episodic character from the sitcom Married... with Children.
    • In , Seven of Nine (also called Seven for short) is one of the crewmembers.
    • In an episode of Seinfeld entitled "The Seven", the name George Costanza desired to give his first-born (with Susan Ross) is "Seven;" he later falsely claimed that he had promised this to the widow of baseball great Mickey Mantle, whose uniform number was 7.
    • The name of a television show 7th Heaven.
    • Seven Network, a television network in Australia.
    • Maximum number of VHF broadcast channels available in any TV market in the United States of America; they are channels 2, 4, 5, 7, 9, 11, and 13 in the Greater New York City and Los Angeles-Long Beach SMSAs.
    • In Stargate SG-1 and Stargate Atlantis, most gate addresses use 7 chevrons on the gate.
    • Ultra Seven, a television series aired in 1967, and the superhero of the same name. He is the honorary seventh member of the Ultra Garrison.
    • The name of a memorable The Adventures of Super Mario Bros. 3 cartoon, 7 Continents for 7 Koopas.

    In film

    In literature

    In video games

    • 7 is a number used many times by Bungie Studios in their Halo and Marathon games. 7 appears in a variety of different contexts, from the stories of the games to the raw game coding. One obvious example is the fact that there are seven Halo rings strewn throughout the galaxy.
    • Final Fantasy VII has many instances of seven throughout the game and was even released (in North America) on the seventh day of September ("September" originally meant "seventh month") in 1997.
    • In the Sonic the Hedgehog games, Sonic collects seven Chaos Emeralds (after completing special stages) which, after getting all of them and then collecting at least 50 rings, allow him to turn into Super Sonic. This transformation makes him glow golden yellow and allows him to move at speeds much faster than he already moves (at the speed of sound[3]). Sonic 3 & Knuckles allows for an even more powerful transformation called 'Hyper Sonic' once an additional seven 'Super Emeralds' are collected.
    • 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.
    • In the Super Mario RPG/Paper Mario series of games, the collection of seven mystical items (predominantly stars, but also hearts in Super Paper Mario) is the main quest of the game.
    • In , 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 upcoming video game .

    In sports

    In other fields

    • Seven is the smallest positive integer requiring more than one syllable in English.
    • The British fifty-pence and twenty-pence coins are heptagons, with the sides curved to give them a constant diameter. Adding them gives you seventy pence
    • 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 Constitution, as drafted in Philadelphia in 1787, was composed of 7 Articles.
    • The United States declared Independence in the 7th month of 1776.
    • In a standard deck of playing cards the 7 of Diamonds is the only diamond card that can be viewed as upside down when reversed.
    • Lotto Super 7, a Canadian-lottery game
    Seven is also:

    Names and titles

    • Sevens, a card game.
    • An agency of photojournalists founded by seven photographers.
    • Canadian fashion photographer Sev Seven.
    • California graffiti artist Seven
    • The Seven Virgins:
    • 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.
    • Seven of Nine, a crew member in the Star Trek universe.
    • 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 Catalan culture, seven is present in a lot of popular stories like "Les set cabretes i el llop".
    • Number 7 is a popular brand of Canadian cigarettes.
    • "The Seven", also written: "The Se7en" is an exclusive grouping of dental surgeons.
    • 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
    • 7-ip is the name of an Australian satellite and wireless technology start up
    • The Ultra Series has two heroes with "Seven" in their name: Ultra Seven and Ultra Seven-21.
    • SEVEN Networks is a US company producing mobile email software.
    • The circle 7 logo used by numerous ABC network O&O stations in the United States.
    • In a survey in England seven was discovered to be the most common lucky number in the 2000 people that were surveyed.

    Notes

    1. ^ 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
    2. ^ "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.'".
[1] The value of 490 suggested by Jesus has been the source of much debate among scholars. For example, did he actually mean to impose a limit at 490, or did he only mean that the number of times (one should be forgiven) is to be ongoing? Most conclude the latter. Alternatively, it may be that the New Testament's mention of seventy "times" seven is a mistranslation of the original Hebrew based on the statement of Lemech (Genesis 4:24) that "If Cain shall be avenged sevenfold, then for Lemech it shall be seventy-sevenfold."
3. ^ Matte, Jared. Sonic Encyclopaedia: Sonic the Hedgehog. The GHZ. Retrieved on 2007-05-12.

See also

References

<references/>
  • Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group. (1987): 70 - 71

External links

0 (zero) is both a number and a numerical digit used to represent that number in numerals. It plays a central role in mathematics as the additive identity of the integers, real numbers, and many other algebraic structures.
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0 1 2 3 4 5 6 7 8 9

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2 (two) is a number, numeral, and glyph. It is the natural number following 1 and preceding 3.

In mathematics

Two has many properties in mathematics.[1] An integer is called even if it is divisible by 2.
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3 (three) is a number, numeral, and glyph. It is the natural number following 2 and preceding 4.

In mathematics

Three is the first odd prime number, and the second smallest positive prime.
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This article discusses the number Four. For the year 4 AD, see 4. For other uses of 4, see 4 (disambiguation)

0 1 2 3 4 5 6 7 8 9

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This article discusses the number five. For the year 5 AD, see 5. For other uses of 5, see 5 (disambiguation).

0 1 2 3 4 5 6 7 8 9

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6 (six) is the natural number following 5 and preceding 7.

The SI prefix for 10006 is exa (E), and for its reciprocal atto (a).

In mathematics

Six is the second smallest composite number, its proper divisors being 1, 2 and 3.
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8 (eight) is the natural number following 7 and preceding 9. The SI prefix for 10008 is yotta (Y), and for its reciprocal yocto (y).

In mathematics

8 is a composite number, its proper divisors being 1, 2, and 4.
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9 (nine) is the natural number following 8 and preceding 10.

In mathematics

Nine is a composite number, its proper divisors being 1 and 3. It is 3 times 3 and hence the third square number. 9 is a Motzkin number. It is the first composite lucky number.
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10 (ten) is an even natural number following 9 and preceding 11.

0

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This is a list of articles about numbers (not about numerals).

Rational numbers

Notable rational numbers

Natural numbers


0 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 26 27 28 29
30 31 32 33 34 35 36 37 38 39
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The integers (from the Latin integer, which means with untouched integrity, whole, entire) are the set of numbers including the whole numbers (0, 1, 2, 3, …) and their negatives (0, −1, −2, −3, …).
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0 (zero) is both a number and a numerical digit used to represent that number in numerals. It plays a central role in mathematics as the additive identity of the integers, real numbers, and many other algebraic structures.
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10 (ten) is an even natural number following 9 and preceding 11.

0

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30 (thirty) is the natural number following 29 and preceding 31.

In mathematics

It is a primorial as well as the sum of the squares of the integers 1, 2, 3 and 4. It is the smallest Giuga number.
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40 (forty) is the natural number following 39 and preceding 41.

Despite being related to the word "four" (4), 40 is spelled as "forty", not "fourty". The letters of the word "forty" are in alphabetical order; this is the only number that has this linguistic property
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50 (fifty) is the integer following 49 and preceding 51.
(the number fifty derives from the two numerical figures of both 0 and 5 placed in order from greatest to least)

In mathematics

Fifty
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60 (sixty) is the natural number following 59 and preceding 61. Being thrice twenty, 60 is called "three score" in some older literature.

In mathematics

Sixty
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70 (seventy) is the natural number following 69 and preceding 71. The French do not have a word for 70, instead using "soixante-dix" (60 + 10). Other French-speaking countries such as Belgium and Switzerland do have a word for it, using "septante.
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80 (eighty) is the natural number following 79 and preceding 81.

In mathematics

The sum of Euler's totient function φ(x) over the first sixteen integers is 80.

Adding up some subsets of its divisors (e.g.
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90 (ninety) is the natural number preceded by 89 and followed by 91.

In mathematics

90 is the sum of the squares of the integers 2 to 6. Because 90 is the sum of its unitary divisors (excluding itself), it is a unitary perfect number, and because it is equal
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100 (one hundred) (the Roman numeral is C for centum) is the natural number following 99 and preceding 101.

In mathematics

One hundred is the square of 10 (in scientific notation it is written as ).
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cardinal numbers, or cardinals for short, are a generalized kind of number used to denote the size of a set, known as its cardinality. For finite sets the cardinality is given by a natural number, being simply the number of elements in the set.
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ordinal, ordinal number, and transfinite ordinal number refer to a type of number introduced by Georg Cantor in 1897, to accommodate infinite sequences and to classify sets with certain kinds of order structures on them.
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numeral system (or system of numeration) is a framework where a set of numbers are represented by numerals in a consistent manner. It can be seen as the context that allows the numeral "11" to be interpreted as the binary numeral for three
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septenary numeral system is the base-7 number system, and uses the digits 0-6.

Fractions expressed in septenary will repeat a sequence of digits unless the denominator is a power of seven.
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factorization (British English: also factorisation) or factoring is the decomposition of an object (for example, a number, a polynomial, or a matrix) into a product of other objects, or factors, which when multiplied together give the original.
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Prime can refer to:
  • Prime number, a natural number which is only divisible by 1 and itself
  • Prime (symbol), the ′ mark
  • 3′ end and 5′ end ("three prime end", "five prime end") in biochemistry

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divisor of an integer n, also called a factor of n, is an integer which evenly divides n without leaving a remainder.

Explanation

For example, 7 is a divisor of 42 because 42/7 = 6.
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