6

This article is about the number. For the years, see 6 BC and AD 6. For other uses, see 6 (disambiguation) and Number Six (disambiguation).

6 (six) is the natural number following 5 and preceding 7. It is a composite number and the smallest perfect number.^[1]

← 654320 654321 654322 →
List of numbers Integers ← 100 101 102 103 104 105 106 107 108 109
Cardinal	six hundred fifty-four thousand three hundred twenty-one
Ordinal	654321st (six hundred fifty-four thousand three hundred twenty-first)
Numeral system	[[senary]123456
Factorization	3 × 218107
Divisors	1, 2, 3, 6
Greek numeral	${\displaystyle {\stackrel {\xi \epsilon }{\mathrm {M} }}}$͵δτκα´
Roman numeral	VI, vi, ↅ
Greek prefix	hexa-/hex-
Latin prefix	sexa-/sex-
Binary	100111111011111100012
Ternary	10200201200103
Senary	220051336
Octal	23757618
Duodecimal	2767A912
Hexadecimal	9FBF116
Greek	στ (or ΣΤ or ς)
Arabic, Kurdish, Sindhi, Urdu	٦
Persian	۶
Amharic	፮
Bengali	৬
Chinese numeral	六，陸
Devanāgarī	६
Gujarati	૬
Hebrew	ו
Khmer	៦
Thai	๖
Telugu	౬
Tamil	௬
Saraiki	٦
Malayalam	൬
Armenian	Զ
Babylonian numeral	𒐚
Egyptian hieroglyph	𓏿
Morse code	_ ....

In mathematics

A six-sided polygon is a hexagon,^[1] one of the three regular polygons capable of tiling the plane. A hexagon also has 6 edges as well as 6 internal and external angles.

6 is the second smallest composite number.^[1] It is also the first number that is the sum of its proper divisors, making it the smallest perfect number.^[2] 6 is the first unitary perfect number, since it is the sum of its positive proper unitary divisors, without including itself. Only five such numbers are known to exist.^[3] 6 is the largest of the four all-Harshad numbers.^[4]

6 is a pronic number,^[5] a congruent number,^[6] a harmonic divisor number, and a semiprime.^[7] 6 is also the first Granville number, or ${\displaystyle {\mathcal {S}}}$-perfect number. A Golomb ruler of length 6 is a "perfect ruler".^[8] 6 is a harmonic divisor number.^[9]

The six exponentials theorem guarantees that under certain conditions one of a set of six exponentials is transcendental.^[10] The smallest non-abelian group is the symmetric group ${\displaystyle \mathrm {S_{3}} }$ which has 3! = 6 elements.^[1] 6 the answer to the two-dimensional kissing number problem.^[11]

A regular cube, with six faces

A cube has 6 faces. A tetrahedron has 6 edges. In four dimensions, there are a total of six convex regular polytopes.

In the classification of finite simple groups, twenty of twenty-six sporadic groups in the happy family are part of three families of groups which divide the order of the friendly giant, the largest sporadic group: five first generation Mathieu groups, seven second generation subquotients of the Leech lattice, and eight third generation subgroups of the friendly giant. The remaining six sporadic groups do not divide the order of the friendly giant, which are termed the pariahs (Ly, O'N, Ru, J₄, J₃, and J₁).^[12]

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	25	50	100	1000
6 × x	6	12	18	24	30	36	42	48	54	60	66	72	78	84	90	96	102	108	114	120	150	300	600	6000

Division	1	2	3	4	5	6	7	8	9	10		11	12	13	14	15
6 ÷ x	6	3	2	1.5	1.2	1	0.857142	0.75	0.6	0.6		0.54	0.5	0.461538	0.428571	0.4
x ÷ 6	0.16	0.3	0.5	0.6	0.83	1	1.16	1.3	1.5	1.6		1.83	2	2.16	2.3	2.5

Exponentiation	1	2	3	4	5	6	7	8	9	10		11	12	13
6x	6	36	216	1296	7776	46656	279936	1679616	10077696	60466176		362797056	2176782336	13060694016
x6	1	64	729	4096	15625	46656	117649	262144	531441	1000000		1771561	2985984	4826809

Greek and Latin word parts

Hexa

Hexa is classical Greek for "six".^[1] Thus:

• "Hexadecimal" combines hexa- with the Latinate decimal to name a number base of 16^[13]
• A hexagon is a regular polygon with six sides^[14]
  • L'Hexagone is a French nickname for the continental part of Metropolitan France for its resemblance to a regular hexagon
• A hexahedron is a polyhedron with six faces, with a cube being a special case^[15]
• Hexameter is a poetic form consisting of six feet per line
• A "hex nut" is a nut with six sides, and a hex bolt has a six-sided head
• The prefix "hexa-" also occurs in the systematic name of many chemical compounds, such as hexane which has 6 carbon atoms (C₆H₁₄).

The prefix sex-

Sex- is a Latin prefix meaning "six".^[1] Thus:

• Senary is the ordinal adjective meaning "sixth"^[16]
• People with sexdactyly have six fingers on each hand
• The measuring instrument called a sextant got its name because its shape forms one-sixth of a whole circle
• A group of six musicians is called a sextet
• Six babies delivered in one birth are sextuplets
• Sexy prime pairs – Prime pairs differing by six are sexy, because sex is the Latin word for six.^[17][18]

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

Evolution of the Hindu-Arabic digit

The first appearance of 6 is in the Edicts of Ashoka c. 250 BCE. These are Brahmi numerals, ancestors of Hindu-Arabic numerals.

The first known digit "6" in the number "256" in Ashoka's Minor Rock Edict No.1 in Sasaram, c. 250 BCE

The evolution of our modern digit 6 appears rather simple when compared with the other digits. The modern 6 can be traced back to the Brahmi numerals of India, which are first known from the Edicts of Ashoka c. 250 BCE.^{[19][20][21][22]} It was written in one stroke like a cursive lowercase e rotated 90 degrees clockwise. Gradually, the upper part of the stroke (above the central squiggle) became more curved, while the lower part of the stroke (below the central squiggle) became straighter. The Arabs dropped the part of the stroke below the squiggle. From there, the European evolution to our modern 6 was very straightforward, aside from a flirtation with a glyph that looked more like an uppercase G.^[23]

On the seven-segment displays of calculators and watches, 6 is usually written with six segments. Some historical calculator models use just five segments for the 6, by omitting the top horizontal bar. This glyph variant has not caught on; for calculators that can display results in hexadecimal, a 6 that looks like a "b" is not practical.

Just as in most modern typefaces, in typefaces with text figures the character for the digit 6 usually has an ascender, as, for example, in .^[24]

This digit resembles an inverted 9. To disambiguate the two on objects and documents that can be inverted, the 6 has often been underlined, both in handwriting and on printed labels.

In music

A standard guitar has six strings.

In artists

• Les Six ("The Six" in English) was a group consisting of the French composers Georges Auric, Louis Durey, Arthur Honegger, Darius Milhaud, Francis Poulenc and Germaine Tailleferre in the 1920s^[25]
• Bands with the number six in their name include Six Organs of Admittance,^[26] 6 O'Clock Saints, Electric Six,^[27] Eve 6, Los Xey (sei is Basque for "six"), Out On Blue Six, Six In Six, Sixpence None the Richer,^[28] Slant 6,^[29] Vanity 6, and You Me At Six^[30]
• #6 is the pseudonym of American musician Shawn Crahan, when performing with the band Slipknot

In instruments

• A standard guitar has six strings^[31]
• Most woodwind instruments have six basic holes or keys (e.g., bassoon, clarinet, pennywhistle, saxophone); these holes or keys are usually not given numbers or letters in the fingering charts

In music theory

• There are six whole tones in an octave.^[32]
• There are six semitones in a tritone.^[33]

In works

• "Six geese a-laying" were given as a present on the sixth day in the popular Christmas carol, "The Twelve Days of Christmas".^[34]
• Divided in six arias, Hexachordum Apollinis is generally regarded as one of the pinnacles of Johann Pachelbel's oeuvre.^[35]
• The theme of the sixth album by Dream Theater, Six Degrees of Inner Turbulence, was the number six: the album has six songs, and the sixth song—that is, the complete second disc—explores the stories of six individuals suffering from various mental illnesses.^[36]
• Aristotle gave six elements of tragedy, the first of which is Mythos.^[37]

In religion

See also: 666

Judaism

• Six points on a Star of David^[38]
• Six orders of the Mishnah^[39]
• Six symbolic foods placed on the Passover Seder Plate^[40]
• God took six days to create the world in the Old Testament Book of Genesis;^[41] humankind was created on day 6. In the City of God, Augustine of Hippo suggested (book 11, chapter 30) that God's creation of the world took six days because 6 is a perfect number.^[42]
• The Jewish holiday of Shavuot starts on the sixth day of the Hebrew month of Sivan^[43]
• Seraphs have six wings.^[44]

Islam

• There are Six articles of faith^[45]
• Six points on a Seal of Solomon
• Fasting six days of Shawwal, together with the month of Ramadan, is equivalent to fasting the whole year^[46]
• The heavens and earth were created in six days according to the Quran:^[47]

Indeed, We created the heavens and the earth and everything in between in six Days,¹ and We were not ˹even˺ touched with fatigue.²

— Surah Qaf:38

Note 1: The word day is not always used in the Quran to mean a 24-hour period. According to Surah Al-Hajj (The Pilgrimage):47, a heavenly Day is 1000 years of our time. The Day of Judgment will be 50,000 years of our time - Surah Al-Maarij (The Ascending Stairways):4. Hence, the six Days of creation refer to six eons of time, known only by Allah.

Note 2: Some Islamic scholars believe this verse comes in response to Exodus 31:17, which says, "The Lord made the heavens and the earth in six days, but on the seventh day He rested and was refreshed."

Others

• In Hindu theology, a trasarenu is the combination of six celestial paramānus (atoms).
• In Taoism:
  • Six Lines of a Hexagram
  • Six Ministries of Huang Di^[48]

In science

Astronomy

• Messier object M6, a magnitude 4.5 open cluster in the constellation Scorpius, also known as the Butterfly Cluster^[49]
• The New General Catalogue object NGC 6, a spiral galaxy in the constellation Andromeda
• The Roman numeral VI:
  • Stands for subdwarfs in the Yerkes spectral classification scheme
  • (Usually) stands for the sixth-discovered satellite of a planet or minor planet (e.g. Jupiter VI)
• 6 Hebe, a large main-belt asteroid.
• A six-sided cloud pattern persists around the north pole on the planet Saturn.

Biology

The cells of a beehive are six-sided.

• The cells of a beehive are six-sided.^[50]
• Insects have six legs (see Hexapoda).^[51]
• Six kingdoms in the taxonomic rank below domain (biology); Animalia, Plantae, Fungi, Protista, Archaea/Archaeabacteria, and Bacteria/Eubacteria. See Kingdom (biology).^[52]
• The six elements most common in biomolecules are called the CHNOPS elements; the letters stand for the chemical abbreviations of carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. See CHON.^[53]

Chemistry

A molecule of benzene has a ring of six carbon and six hydrogen atoms.

• A benzene molecule has a ring of six carbon atoms.^[54]
• 6 is the atomic number of carbon.^[55] Carbon-12, its most stable isotope, has six protons, six nuetrons, and six electrons.
• The sixfold symmetry of snowflakes arises from the hexagonal crystal structure of ordinary ice.^[56]
• A hexamer is an oligomer made of six subunits.
• The p-orbital allows an element to bind up to a maximum of six electrons.

Medicine

• There are six tastes in traditional Indian medicine (Ayurveda): sweet, sour, salty, bitter, pungent, and astringent. These tastes are used to suggest a diet based on the symptoms of the body.^[57]
• Phase 6 is one of six pandemic influenza phases.^[58]

Physics

In the Standard Model of particle physics, there are six types of quarks and six types of leptons.

• In the Standard Model of particle physics, there are six types of quarks and six types of leptons.^[59]
• In statistical mechanics, the six-vertex model has six possible configurations of arrows at each vertex^[60]
• There are six colors in the RGB color wheel: (primary) red, blue, green, (secondary) cyan, magenta, and yellow. (See Tertiary color)^[61]
• In three-dimensional Euclidean space, there are six unknown support reactions for a statically determinate structure: one force in each of the three dimensions, and one moment through each of three possible orthogonal planes.

In technology

6 as a resin identification code, used in recycling.

• On most phones, the 6 key is associated with the letters M, N, and O, but on the BlackBerry Pearl it is the key for J and K, and on the BlackBerry 8700 series and Curve 8900 with full keyboard, it is the key for F
• The "6-meter band" in amateur radio includes the frequencies from 50 to 54 MHz
• 6 is the resin identification code used in recycling to identify polystyrene^[62]

In calendars

• In the ancient Roman calendar, Sextilis was the sixth month. After the Julian reform, June became the sixth month and Sextilis was renamed August^[63]
• Sextidi was the sixth day of the décade in the French Revolutionary calendar^[64]

Anthropology

• The name of the smallest group of Cub Scouts and Guiding's equivalent Brownies, traditionally consisting of six people and is led by a "sixer".
• A coffin is traditionally buried six feet under the ground; thus, the phrase "six feet under" means that a person (or thing, or concept) is dead^[65]
• There are said to be no more than six degrees of separation between any two people on Earth.^[66]
• In Western astrology, Virgo is the 6th astrological sign of the Zodiac^[67]
• The Six Dynasties form part of Chinese history^[68]
• Six is a lucky number in Chinese culture.^{[citation needed]}
• The Birmingham Six were a British miscarriage of justice, held in prison for 16 years.^[69]
• "Six" is used as an informal slang term for the British Secret Intelligence Service, MI6.^[70]

See also

• List of highways numbered 6
• Six degrees (disambiguation).

References

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2. Higgins, Peter (2008). Number Story: From Counting to Cryptography. New York: Copernicus. p. 11. ISBN 978-1-84800-000-1.
3. Sloane, N. J. A. (ed.). "Sequence A002827 (Unitary perfect numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-01.
4. Weisstein, Eric W. "Harshad Number". mathworld.wolfram.com. Retrieved 2020-08-03.
5. "Sloane's A002378: Pronic numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2020-11-30.
6. Sloane, N. J. A. (ed.). "Sequence A003273 (Congruent numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-01.
7. Sloane, N. J. A. (ed.). "Sequence A001358 (Semiprimes (or biprimes): products of two primes.)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2023-08-03.
8. Bryan Bunch, The Kingdom of Infinite Number. New York: W. H. Freeman & Company (2000): 72
9. Sloane, N. J. A. (ed.). "Sequence A001599 (Harmonic or Ore numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-06-01.
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11. Weisstein, Eric W. "Kissing Number". mathworld.wolfram.com. Retrieved 2020-08-03.
12. Griess, Jr., Robert L. (1982). "The Friendly Giant" (PDF). Inventiones Mathematicae. 69: 91–96. Bibcode:1982InMat..69....1G. doi:10.1007/BF01389186. hdl:2027.42/46608. MR 0671653. S2CID 123597150. Zbl 0498.20013.
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23. 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. 24.66
24. Negru, John (1988). Computer Typesetting. Van Nostrand Reinhold. p. 59. ISBN 978-0-442-26696-7. slight ascenders that rise above the cap height ( in 4 and 6 )
25. Auric, Georges; Durey, Louis; Honegger, Arthur; Milhaud, Darius; Poulenc, Francis; Tailleferre, Germaine (2014-08-20). Caramel Mou and Other Great Piano Works of "Les Six": Pieces by Auric, Durey, Honegger, Milhaud, Poulenc and Tailleferre (in French). Courier Corporation. ISBN 978-0-486-49340-4.
26. "Six Organs of Admittance". www.sixorgans.com. Retrieved 2020-08-03.
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28. "Sixpence None The Richer". GRAMMY.com. 2020-05-19. Retrieved 2020-08-04.
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31. "Definition of GUITAR". www.merriam-webster.com. Retrieved 2020-08-04.
32. D'Amante, Elvo (1994-01-01). Music Fundamentals: Pitch Structures and Rhythmic Design. Scarecrow Press. p. 194. ISBN 978-1-4616-6985-2. The division of an octave into six equal parts is referred to as the whole-tone scale
33. Horsley, Charles Edward (1876). A Text Book of Harmony: For the Use of Schools and Students. Sampson Low, Marston, Searle, & Rivington. p. 4. Like the Tritone, it contains six semitones
34. Tribble, Mimi (2004). 300 Ways to Make the Best Christmas Ever!: Decorations, Carols, Crafts & Recipes for Every Kind of Christmas Tradition. Sterling Publishing Company, Inc. p. 145. ISBN 978-1-4027-1685-0. Six geese a-laying
35. Staines, Joe (2010-05-17). The Rough Guide to Classical Music. Penguin. p. 393. ISBN 978-1-4053-8321-9. ...the six arias with variations collected under the title Hexachordum Apollinis (1699)...
36. Hegarty, Paul; Halliwell, Martin (2011-06-23). Beyond and Before: Progressive Rock since the 1960s. Bloomsbury Publishing USA. p. 169. ISBN 978-1-4411-1480-8. Six Degrees of Inner Turbulence
37. Curran, Angela (2015-10-05). Routledge Philosophy Guidebook to Aristotle and the Poetics. Routledge. p. 133. ISBN 978-1-317-67706-2. THE SIX QUALITATIVE ELEMENTS OF TRAGEDY
38. Plaut, W. Gunther (1991). The Magen David: How the Six-pointed Star Became an Emblem for the Jewish People. B'nai B'rith Books. ISBN 978-0-910250-16-0. How the Six-pointed Star Became an Emblem for the Jewish People
39. Lauterbach, Jacob Zallel (1916). Midrash and Mishnah: A Study in the Early History of the Halakah. Bloch. p. 9. Six orders of Mishnah
40. Rosen, Ceil; Rosen, Moishe (2006-05-01). Christ in the Passover. Moody Publishers. p. 79. ISBN 978-1-57567-480-3. Six symbolic foods
41. Repcheck, Jack (2008-12-15). The Man Who Found Time: James Hutton And The Discovery Of Earth's Antiquity. Basic Books. ISBN 978-0-7867-4399-5. it actually took only six days to create the earth
42. "CHURCH FATHERS: City of God, Book XI (St. Augustine)". www.newadvent.org. Retrieved 2020-08-04. These works are recorded to have been completed in six days (the same day being six times repeated), because six is a perfect number
43. Grossman, Grace Cohen; Ahlborn, Richard E.; Institution, Smithsonian (1997). Judaica at the Smithsonian: Cultural Politics as Cultural Model. Smithsonian Institution Press. p. 228. Shavuot falls on the sixth day of the Hebrew month of Sivan
44. Robertson, William Archibald Scott (1880). The crypt of Canterbury cathedral; its architecture, its history, and its frescoes. Mitchell & Hughes. p. 91. ...but seraphs, with six wings
45. Shapera, Paul M. (2009-08-15). Iran's Religious Leaders. The Rosen Publishing Group, Inc. p. 10. ISBN 978-1-4358-5283-9. Islam has six articles of faith
46. Algül, Hüseyin (2005). The Blessed Days and Nights of the Islamic Year. Tughra Books. p. 65. ISBN 978-1-932099-93-5. ...it was blessed to fast for six days in the month of Shawwal...
47. "Surah Qaf - 38". Quran.com. Retrieved 2023-08-28.
48. Bary, William Theodore De; DeBary, William T.; Chan, Wing-tsit; Lufrano, Richard; Ching, Julia; Johnson, David; Liu, Kwang-Ching; Mungello, David (1999). Sources of Chinese Tradition. Columbia University Press. ISBN 978-0-231-11270-3. ...and the Six Ministries were made...
49. Rhoads, Samuel E. (1996). The Sky Tonight: A Guided Tour of the Stars Over Hawaiʻi. Bishop Museum Press. ISBN 978-0-930897-93-2. Three Messier objects are visible in this part of the sky : M6, M7 and M8 .
50. Sedgwick, Marcus (2011-07-05). White Crow. Roaring Brook Press. p. 145. ISBN 978-1-4299-7634-3. The cells of honeycombs are six-sided because a hexagon is the most material-efficient tessellation
51. Parker, Steve (2005). Ant Lions, Wasps & Other Insects. Capstone. p. 16. ISBN 978-0-7565-1250-7. Insects have six legs each...
52. Pendarvis, Murray P.; Crawley, John L. (2019-02-01). Exploring Biology in the Laboratory: Core Concepts. Morton Publishing Company. p. 10. ISBN 978-1-61731-899-3. ...presently at least six kingdoms are recognized;
53. Mader, Sylvia S. (2004). Biology. McGraw-Hill. p. 20. ISBN 978-0-07-291934-9. The acronym CHNOPS helps us remember these six elements
54. Dufour, Fritz (2018-09-19). The Realities of Reality - Part II: Making Sense of Why Modern Science Advances. Vol. 1. Fritz Dufour. p. 100. The benzene molecule has its six carbon atoms in a ring^{[self-published source?]}
55. Starr, Cecie; Evers, Christine (2012-05-10). Biology Today and Tomorrow without Physiology. Cengage Learning. p. 25. ISBN 978-1-133-36536-5. For example, the atomic number of carbon is 6,
56. Webb, Stephen; Webb, Professor of Australian Studies Stephen (2004-05-25). Out of this World: Colliding Universes, Branes, Strings, and Other Wild Ideas of Modern Physics. Springer Science & Business Media. p. 16. ISBN 978-0-387-02930-6. snowflake, with its familiar sixfold rotational symmetry
57. Woo, Teri Moser; Robinson, Marylou V. (2015-08-03). Pharmacotherapeutics For Advanced Practice Nurse Prescribers. F.A. Davis. p. 145. ISBN 978-0-8036-4581-3. Ayurvedic herbology is based on the tridoshic theory that there exist six basic tastes
58. Pandemic Influenza Preparedness and Response Guidance for Healthcare Workers and Healthcare Employers. OSHA, U.S. Department of Labor. 2007. p. 8. The WHO Plan describes six phases of increasing public health risk associated with the emergence of a new influenza
59. Sanghera, Paul (2011-03-08). Quantum Physics for Scientists and Technologists: Fundamental Principles and Applications for Biologists, Chemists, Computer Scientists, and Nanotechnologists. John Wiley & Sons. p. 64. ISBN 978-0-470-92269-9. ...there are six types of quarks and six types of leptons.
60. Jimbo, M.; Jimbo, Michio; Miwa, Tetsuji; Tsuchiya, Akihiro (1989). Integrable Systems in Quantum Field Theory and Statistical Mechanics. Academic Press. p. 588. ISBN 978-0-12-385342-4. Allowed configurations in the six-vertex model and their statistical weights
61. Sloan, Robin James Stuart (2015-05-07). Virtual Character Design for Games and Interactive Media. CRC Press. p. 34. ISBN 978-1-4665-9820-1. placing six primaries around the wheel in the following order: red, yellow, green, cyan, blue, magenta.
62. Stevens, E. S. (2002). Green Plastics: An Introduction to the New Science of Biodegradable Plastics. Princeton University Press. p. 45. ISBN 978-0-691-04967-0.
63. Bunson, Matthew (2014-05-14). Encyclopedia of the Roman Empire. Infobase Publishing. p. 90. ISBN 978-1-4381-1027-1. Augustus was also originally called Sextilis, the sixth month.
64. Nicolas, Sir Nicholas Harris (1833). The Chronology of History: Containing Tables, Calculations and Statements, Indispensable for Ascertaining the Dates of Historical Events and of Public and Private Documents from the Earliest Period to the Present Time. Longham, Rees, Orme, Brown, Green, & Longman and John Taylor. p. 172. SEXTIDI, or " Jour de la Révolution, "
65. Rimes, Wendy (2016-04-01). "The Reason Why The Dead Are Buried Six Feet Below The Ground". Elite Readers. Retrieved 2020-08-06.
66. "Six Degrees of Peggy Bacon". www.aaa.si.edu. 27 June 2012. Retrieved 2020-08-06.
67. "Virgo | constellation and astrological sign". Encyclopedia Britannica. Retrieved 2020-08-06.
68. Wilkinson, Endymion Porter; Wilkinson, Scholar and Diplomat (Eu Ambassador to China 1994-2001) Endymion (2000). Chinese History: A Manual. Harvard Univ Asia Center. p. 11. ISBN 978-0-674-00249-4.{{cite book}}: CS1 maint: numeric names: authors list (link)
69. Peirce, Gareth (2011-03-12). "The Birmingham Six: Have we learned from our disgraceful past?". The Guardian. ISSN 0261-3077. Retrieved 2020-08-06.
70. Smith, Michael (2011-10-31). Six: The Real James Bonds 1909-1939. Biteback Publishing. ISBN 978-1-84954-264-7.

• The Odd Number 6, JA Todd, Math. Proc. Camb. Phil. Soc. 41 (1945) 66–68
• A Property of the Number Six, Chapter 6, P Cameron, JH v. Lint, Designs, Graphs, Codes and their Links ISBN 0-521-42385-6
• Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group. (1987): 67 - 69

External links

• The Number 6
• The Positive Integer 6
• Prime curiosities: 6