# 42 (number)

 ← 41 42 43 →
Cardinalforty-two
Ordinal42nd
(forty-second)
Factorization2 × 3 × 7
Divisors1, 2, 3, 6, 7, 14, 21, 42
Greek numeralΜΒ´
Roman numeralXLII
Binary1010102
Ternary11203
Senary1106
Octal528
Duodecimal3612

42 (forty-two) is the natural number that follows 41 and precedes 43.

## Mathematics

Forty-two (42) is a pronic number[1] and an abundant number; its prime factorization (${\displaystyle 2\times 3\times 7}$) makes it the second sphenic number and also the second of the form (${\displaystyle 2\times 3\times r}$).

Additional properties of the number 42 include:

• It is the number of isomorphism classes of all simple and oriented directed graphs on 4 vertices. In other words, it is the number of all possible outcomes (up to isomorphism) of a tournament consisting of 4 teams where the game between any pair of teams results in three possible outcomes: the first team wins, the second team wins, or there is a draw. The group stage of the FIFA World cup is a good example.
• It is the third primary pseudoperfect number.[2]
• It is a Catalan number.[3] Consequently, 42 is the number of noncrossing partitions of a set of five elements, the number of triangulations of a heptagon, the number of rooted ordered binary trees with six leaves, the number of ways in which five pairs of nested parentheses can be arranged, etc.
• It is an alternating sign matrix number, that is, the number of 4-by-4 alternating sign matrices.
• It is the smallest number k that is equal to the sum of the nonprime proper divisors of k, i.e., 42 = 1 + 6 + 14 + 21.
• It is the number of partitions of 10—the number of ways of expressing 10 as a sum of positive integers (note a different sense of partition from that above).
• 1111123, one of the 42 unordered integer partitions of 10 has 42 ordered compositions, since 7!/5!=42.
• The angle of 42 degrees can be constructed with only compass and straight edge and using the golden ratio in 18 degree, i.e. the difference between constructible angles 60 and 18.
• Given 27 same-size cubes whose nominal values progress from 1 to 27, a 3 × 3 × 3 magic cube can be constructed such that every row, column, and corridor, and every diagonal passing through the center, is composed of three numbers whose sum of values is 42.
• It is the third pentadecagonal number.[4] It is a meandric number and an open meandric number.
• 42 is the only known value that is the number of sets of four distinct positive integers a, b, c, d, each less than the value itself, such that abcd, acbd, and adbc are each multiples of the value. Whether there are other values remains an open question.[5]
• 42 is a (2,6)-perfect number (super-multiperfect), as σ2(n) = σ(σ(n)) = 6n.[6]
• 42 is the resulting number of the original Smith number (${\displaystyle 4937775=3\times 5\times 5\times 65837}$): Both the sum of its digits (${\displaystyle 4+9+3+7+7+7+5}$) and the sum of the digits in its prime factorization (${\displaystyle 3+5+5+(6+5+8+3+7)}$) result in 42.
• The dimension of the Borel subalgebra in the exceptional Lie algebra e6 is 42.
• 42 is the largest number n such that there exist positive integers p, q, r with 1 = 1/n + 1/p + 1/q + 1/r
• 42 is the smallest number k such that for every Riemann surface C of genus ${\displaystyle g\geq 2}$, #Aut(C) ≤ k deg(KC) = k(2g − 2) (Hurwitz's automorphisms theorem)
• 42 is the sum of the first six positive even numbers.
• 42 was the last natural number less than 100 whose representation as a sum of three cubes was found (in 2019). The representation is: ${\displaystyle (-80538738812075974)^{3}+80435758145817515^{3}+12602123297335631^{3}}$.[7]
• 42 is a Harshad number in base 10, because the sum of the digits 4 and 2 is 6 (4 + 2 = 6), and 42 is divisible by 6.
• 42 is the number of ways to arrange the numbers 1 to 9 in a 3x3 matrix such that the numbers in each row and column are in ascending order.
• 42 is also ten factorial divided by the number of seconds in a day (i.e. 86400).

## Science

• 42 is the atomic number of molybdenum.
• 42 is the atomic mass of one of the naturally occurring stable isotopes of calcium.
• The angle rounded to whole degrees for which a rainbow appears (the critical angle).
• In 1966, mathematician Paul Cooper theorized that the fastest, most efficient way to travel across continents would be to bore a straight hollow tube directly through the Earth, connecting a set of antipodes, remove the air from the tube and fall through.[8] The first half of the journey consists of free-fall acceleration, while the second half consists of an exactly equal deceleration. The time for such a journey works out to be 42 minutes. Even if the tube does not pass through the exact center of the Earth, the time for a journey powered entirely by gravity (known as a gravity train) always works out to be 42 minutes, so long as the tube remains friction-free, as while the force of gravity would be lessened, the distance traveled is reduced at an equal rate.[9][10] (The same idea was proposed, without calculation by Lewis Carroll in 1893 in Sylvie and Bruno Concluded.[11]) Now we know that is inaccurate, and it only would take about 38 minutes.[12]
• As determined by the Babylonians, in 79 years Mars orbits the Sun almost exactly 42 times.[13]
• The hypothetical efficiency of converting mass to energy, as per E=mc², by having a given mass orbit a rotating black hole is 42%, the highest efficiency yet known to modern physics.[14]
• In Powers of Ten by Ray and Charles Eames, the known universe from large-scale to small-scale is represented by 42 different powers of ten. These powers range from 1025 meters to 10−17 meters.

## Religion

• Ancient Egyptian religion: Over most of pharaonic Egyptian history, the empire was divided into 42 nomes. Ancient Egyptian religion and mythological structure frequently model this terrestrial structure.[18]
• 42 body parts of Osiris: In some traditions of the Osiris myth, Seth slays Osiris and distributes his 42 body parts all over Egypt. (In others, the number is fourteen and sixteen).[19]
• 42 negative confessions: In Ancient Egyptian religion, the 42 negative confessions were a list of questions asked of deceased persons making their journey through the underworld after death. Ma'at was an abstract concept representing moral law, order, and truth in both the physical and moral spheres, as well as being an important goddess in the religion. In the judgment scene described in the Egyptian Book of the Dead, which evolved from the Coffin Texts and the Pyramid Texts, 42 questions were asked of the deceased person as part of the assessment of Ma'at. If the deceased person could reasonably give answers to the 42 questions, they would be permitted to enter the afterlife. These 42 questions are known as the "42 Negative Confessions" and can be found in funerary texts such as the Papyrus of Ani.
• 42 books in the core library: Clement of Alexandria states that the Egyptian temple library is divided into 42 "absolutely necessary" books that formed the stock of a core library. 36 contain the entire philosophy of the Egyptians which are memorized by the priests. While the remaining 6, are learned by the Pastophoroi (image-bearers).[20][21] (36 is like-wise a sacred number in Egyptian thought, related to time, in particular the thirty-six Decan stars and the thirty-six, 10-day "weeks" in the Egyptian year.[22]) The 42 books were not canonized like the Hebrew bible; they only supported and never replaced temple ritual. Hence, the destruction of the Egyptian temples and the cessation of the rituals ended Egyptian cultural continuity.[23]
• Abrahamic religions
• There are 42 Stations of the Exodus which are the locations visited by the Israelites following their exodus from Egypt, recorded in Numbers 33, with variations also recorded in the books of Exodus and Deuteronomy.
• In 2 Kings 2:24, the she-bears summoned by Elisha kill forty-two boys.
• In Judaism, the number (in the Babylonian Talmud, compiled 375 AD to 499 AD) of the "Forty-Two Lettered Name" ascribed to God. Rab (or Rabhs), a 3rd-century source in the Talmud stated "The Forty-Two Lettered Name is entrusted only to him who is pious, meek, middle-aged, free from bad temper, sober, and not insistent on his rights". [Source: Talmud Kidduschin 71a, Translated by Rabbi I. Epstein]. Maimonides felt that the original Talmudic Forty-Two Lettered Name was perhaps composed of several combined divine names [Maimonides "Moreh"]. The apparently unpronouncable Tetragrammaton provides the backdrop from the Twelve-Lettered Name and the Forty-Two Lettered Name of the Talmud.[citation needed]
• In Judaism, by some traditions the Torah scroll is written with no fewer than 42 lines per column, based on the journeys of Israel.[24] In the present day, 42 lines is the most common standard,[25] but various traditions remain in use (see Sefer Torah).
• 42 is the number with which God creates the Universe in Kabbalistic tradition. In Kabbalah, the most significant name is that of the En Sof (also known as "Ein Sof", "Infinite" or "Endless"), who is above the Sefirot (sometimes spelled "Sephirot").[26] The Forty-Two-Lettered Name contains four combined names which are spelled in Hebrew letters (spelled in letters = 42 letters), which is the name of Azilut (or "Atziluth" "Emanation"). While there are obvious links between the Forty-Two Lettered Name of the Babylonian Talmud and the Kabbalah's Forty-Two Lettered Name, they are probably not identical because of the Kabbalah's emphasis on numbers. The Kabbalah also contains a Forty-Five Lettered Name and a Seventy-Two Lettered Name.
• The number 42 appears in various contexts in Christianity. There are 42 generations (names) in the Gospel of Matthew's version of the Genealogy of Jesus; it is prophesied that for 42 months the Beast will hold dominion over the Earth (Revelation 13:5); 42 men of Beth-azmaveth were counted in the census of men of Israel upon return from exile (Ezra 2:24); God sent bears to maul 42 of the teenage boys who mocked Elisha for his baldness (2 Kings 2:23), etc.
• The Gutenberg Bible is also known as the "42-line Bible", as the book contained 42 lines per page.
• The Forty-Two Articles (1552), largely the work of Thomas Cranmer, were intended to summarize Anglican doctrine, as it now existed under the reign of Edward VI.
• East Asian religions
• The Sutra of Forty-two Sections is a Buddhist scripture.
• In Japanese culture, the number 42 is considered unlucky because the numerals when pronounced separately—shi ni (four two)—sound like the word "dying",[27] like the Latin word "mori".

## Popular culture

### The Hitchhiker's Guide to the Galaxy

The number 42 is, in The Hitchhiker's Guide to the Galaxy by Douglas Adams, the "Answer to the Ultimate Question of Life, the Universe, and Everything", calculated by an enormous supercomputer named Deep Thought over a period of 7.5 million years. Unfortunately, no one knows what the question is. Thus, to calculate the Ultimate Question, a special computer the size of a small planet was built from organic components and named "Earth". The Ultimate Question "What do you get when you multiply six by nine"[28] was found by Arthur Dent and Ford Prefect in the second book of the series, The Restaurant at the End of the Universe. This appeared first in the radio play and later in the novelization of The Hitchhiker's Guide to the Galaxy. The fourth book in the series, the novel So Long, and Thanks for All the Fish, contains 42 chapters. According to the novel Mostly Harmless, 42 is the street address of Stavromula Beta. In 1994, Adams created the 42 Puzzle, a game based on the number 42.

The book 42: Douglas Adams' Amazingly Accurate Answer to Life, the Universe and Everything (2011)[29] examines Adams' choice of the number 42, and contains a compendium of some instances of the number in science, popular culture, and humour.

Google also has a calculator easter egg when one searches "the answer to the ultimate question of life, the universe, and everything." Once typed (all in lowercase), the calculator answers with the number 42.[30]

In Hervé Le Tellier's novel The Anomaly, a top-secret US Government protocol receives code number 42, inspired by this source.[citation needed]

### Works of Lewis Carroll

Lewis Carroll, who was a mathematician,[31] made repeated use of this number in his writings.[32]

Examples of Carroll's use of 42:

• Alice's Adventures in Wonderland has 42 illustrations.
• Alice's attempts at multiplication (chapter two of Alice in Wonderland) work if one uses base 18 to write the first answer, and increases the base by threes to 21, 24, etc. (the answers working up to 4 × 12 = "19" in base 39), but "breaks" precisely when one attempts the answer to 4 × 13 in base 42, leading Alice to declare "oh dear! I shall never get to twenty at that rate!"[citation needed]
• Rule Forty-two in Alice's Adventures in Wonderland ("All persons more than a mile high to leave the court").
• Rule 42 of the Code in the preface[33] to The Hunting of the Snark ("No one shall speak to the Man at the Helm").
• In "fit the first" of The Hunting of the Snark the Baker had "forty-two boxes, all carefully packed, With his name painted clearly on each."[34]
• The White Queen announces her age as "one hundred and one, five months and a day", which—if the best possible date is assumed for the action of Through the Looking-Glass (e.g., a date is chosen such that the rollover from February to March is excluded from what would otherwise be an imprecise measurement of "five months and a day")—gives a total of 37,044 days. If the Red Queen, as part of the same chess set, is regarded as the same age, their combined age is 74,088 days, or 42 × 42 × 42.[35]

### Television and film

• The Kumars at No. 42 is a British comedy television series.
• "42" is an episode of Doctor Who, set in real time lasting approximately 42 minutes.
• On the game show Jeopardy!, "Watson" the IBM supercomputer has 42 "threads" in its avatar.[37]
• 42 is a film on the life of American baseball player Jackie Robinson.
• Captain Harlock is sometimes seen wearing clothing with the number 42 on it.
• In the Stargate Atlantis season 4 episode "Quarantine", Colonel Sheppard states that Dr. McKay's password ends in 42 because "It's the ultimate answer to the great question of life, the universe and everything."
• In Star Wars: The Rise of Skywalker, the Festival of the Ancestors on Planet Pasaana is held every 42 years. The film itself was released in 2019, 42 years after the 1977 original Star Wars film. By a "whole string of pretty meaningless coincidences",[38] 2019 is the same year that 42 was found to be the largest possible natural number less than 100 to be expressed as a sum of three cubes.[7]
• In the TV show Lost, 42 is one of the numbers used throughout the show for some of its mysteries.
• There is a Belgian TV drama called Unit 42 about a special police unit that uses high-tech tools to go after criminals. One of the characters in the pilot episode explains that the unit was named based on the Hitchhiker's Guide.

### Architecture

• The architects of the Rockefeller Center in New York City worked daily in the Graybar Building where on "the twenty-fifth floor, one enormous drafting room contained forty-two identical drawing boards, each the size of a six-seat dining room table; another room harboured twelve more, and an additional fourteen stood just outside the principals' offices at the top of the circular iron staircase connecting 25 to 26".[40]
• In the Rockefeller Center (New York City) there are a total of "forty-two elevators in five separate banks"[41] which carry tenants and visitors to the sixty-six floors.

### Comics

• Miles Morales was bitten by a spider bearing the number 42, causing him to become a Spider-Man. The number was later heavily referenced in the film Spider-Man: Into the Spider-Verse. The use of 42 within the franchise references Jackie Robinson's use of the number, though many fans incorrectly believed it to be a The Hitchhiker's Guide to the Galaxy reference.[42]

## References

1. ^ Sloane, N. J. A. (ed.). "Sequence A002378 (Oblong (or promic, pronic, or heteromecic) numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30.
2. ^ Sloane, N. J. A. (ed.). "Sequence A054377 (Primary pseudoperfect numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30.
3. ^ Sloane, N. J. A. (ed.). "Sequence A000108 (Catalan numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30.
4. ^ Sloane, N. J. A. (ed.). "Sequence A051867 (15-gonal (or pentadecagonal) numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30.
5. ^ "Differently Perfect". mathpages.com.
6. ^
7. ^ a b Booker, Andrew R.; Sutherland, Andrew V. (2021), "On a question of Mordell", Proceedings of the National Academy of Sciences, 118 (11), arXiv:2007.01209, Bibcode:2021PNAS..11822377B, doi:10.1073/pnas.2022377118, PMC 7980389, PMID 33692126
8. ^ Cooper, Paul W. (1966). "Through the Earth in Forty Minutes". American Journal of Physics. 34 (1): 68–69. Bibcode:1966AmJPh..34...68C. doi:10.1119/1.1972773.
9. ^ "To Everywhere in 42 Minutes". Time. February 11, 1966. Archived from the original on 12 May 2008. Retrieved 2008-05-18.
10. ^ "Jumping into a 7,965 mile deep hole". YouTube. Archived from the original on June 2, 2008. Retrieved 2008-05-18.
11. ^ Carroll, Lewis (29 December 1893). "Chapter 7". Sylvie and Bruno Concluded. Vol. 2. illustrated by Harry Furniss. United Kingdom: Macmillan and Co. Each railway is in a long tunnel, perfectly straight: so of course the middle of it is nearer the centre of the globe than the two ends: so every train runs half-way down-hill, and that gives it force enough to run the other half up-hill.
12. ^ Choi, Charles Q. (March 31, 2015). "How Long Would It Take to Fall Through the Earth?". livescience.com. Retrieved 2021-06-27.
13. ^ Powell, Martin J. "Ancient astronomy and the naked-eye planets". Eternal Gadgetry. MS. Retrieved January 6, 2018.
14. ^ Cotter, Garrett (2012). "High-Energy Astrophysics Lecture" (PDF). Astrophysics | University of Oxford Department of Physics.
15. ^ Berard (April 2009). "IRIG 106 Telemetry Standard Chapter 10" (PDF). U.S. Army White Sands Missile Range, New Mexico: Range Commanders Council. Archived (PDF) from the original on 2020-11-12. Retrieved 2010-11-10.
16. ^ Lee Middleton; Jayanthi Sivaswamy (2002). "Framework for practical hexagonal-image processing". Journal of Electronic Imaging. 11 (104): 104. Bibcode:2002JEI....11..104M. doi:10.1117/1.1426078.
17. ^ "Maximum password age". Microsoft TechNet. Retrieved 15 January 2014.
18. ^ Assman, Jan (2008). Of God and Gods: Egypt, Israel, and the Rise of Monotheism (George L. Mosse Series in Modern European Cultural and Intellectual History) (Kindle ed.). The University of Wisconsin Press. p. Kindle Location 195. ISBN 978-0299225544.
19. ^ Assman, Jan (2008). Of God and Gods: Egypt, Israel, and the Rise of Monotheism (George L. Mosse Series in Modern European Cultural and Intellectual History) (Kindle ed.). The University of Wisconsin Press. p. Kindle Location 576. ISBN 978-0299225544.
20. ^ Assman, Jan (2008). Of God and Gods: Egypt, Israel, and the Rise of Monotheism (George L. Mosse Series in Modern European Cultural and Intellectual History) (Kindle ed.). The University of Wisconsin Press. p. Kindle Location 1364. ISBN 978-0299225544.
21. ^ Clement of Alexandria (1885). "Book VI:IV". In Roberts, Alexander; James, Sir; Coxe, Arthur (eds.). The Stromata, or Miscellanies (With Active Table of Contents) (Kindle ed.). p. Kindle Location 11498.
22. ^ Assman, Jan (2008). Of God and Gods: Egypt, Israel, and the Rise of Monotheism (George L. Mosse Series in Modern European Cultural and Intellectual History) (Kindle ed.). The University of Wisconsin Press. p. Kindle Location 1380. ISBN 978-0299225544.
23. ^ Assman, Jan (2008). Of God and Gods: Egypt, Israel, and the Rise of Monotheism (George L. Mosse Series in Modern European Cultural and Intellectual History) (Kindle ed.). The University of Wisconsin Press. p. Kindle Location 1418. ISBN 978-0299225544.
24. ^ Ganzfried, R. Solomon (1902). קסת הסופר [Keset haSofer] (in Hebrew and English). Translated by Friendman, Jen (First ed.). Bardejov: דפוס יוסף מאיר בלייער. It is the custom to have no fewer than 48 lines, representing the journeys of Israel, and some say no fewer than 42, because of what God did in the Sinai wilderness at Kadesh. Also, we don't have more than 60 lines, representing the 60 myriads of Israel who received the Torah.
25. ^ Jacobs, Joseph; Eisenstein, Judah; Executive Committee of the Editorial Board; Blau, Ludwig (1906). "Scroll of the Law (Hebrew, "Sefer Torah")". Jewish Encyclopedia. Retrieved 12 February 2020. (At the present day the forty-two-lined column is the generally accepted style of the scroll, its length being about 24 inches.)
26. ^ Joel Primack; Nancy E. Abrams. "In A Beginning...Quantum Cosmology and Kabbalah" (PDF). Retrieved 2008-03-14.
27. ^ Niiya, Brian. Japanese American history: an A-to-Z reference from 1868 to the present. Facts on File, Inc., 1993, p. 352
28. ^ "Mathematical Fiction: Hitchhiker's Guide to the Galaxy (1979)". Retrieved 30 November 2016. See this website for possible explanations of this seeming error.
29. ^ Gill, Peter (February 3, 2011). "42: Douglas Adams' Amazingly Accurate Answer to Life the Universe and Everything". Guardian. London. Retrieved 3 April 2011.
30. ^ "17 amazing Google Easter eggs". CBS News. November 11, 2011. Retrieved November 1, 2022.
31. ^ "Lewis Carroll and Douglas Adams – Word Ways – Find Articles". 29 June 2012. Archived from the original on 29 June 2012.
32. ^ The Mystery of Lewis Carroll, Jenny Woolf
33. ^
34. ^
35. ^ What Lewis Carroll Taught Us: Alice's creator knew all about role-playing. by Seth Lerer, March 4, 2010
36. ^ Walker, Carter (2016-07-15). "REVIEW: Music, not problems, is focus this year at Disco Biscuits' Camp Bisco at Pavilion at Montage". baltimoresun.com. Retrieved 2020-08-17.
37. ^ "Watson Jeopardy! computer: Ken Jennings describes what it's like to play against a machine". Slate. Retrieved 2 October 2015.
38. ^ Adams, Douglas (September 29, 2010). The Ultimate Hitchhiker's Guide to the Galaxy (Kindle ed.). Del Ray. p. 27. ISBN 978-0-307-49846-5.
39. ^ "The Laws of Cricket". Archived from the original on 29 August 2017. Retrieved 26 January 2017.
40. ^ Okrent, Daniel. Great Fortune: the Epic of the Rockefeller Centre. Viking Penguin, 2003, p. 147
41. ^ Okrent, Daniel. Great Fortune: the Epic of the Rockefeller Centre. Viking Penguin, 2003, p. 162
42. ^ Renfro, Kim (February 26, 2019). "Why the number 42 was hidden in plain sight throughout 'Spider-Man: Into the Spider-Verse'". Insider Inc. Retrieved November 29, 2019.
43. ^ "Tower 42 – City of London". cityoflondon.gov.uk. Retrieved 23 October 2018.
44. ^ "42: Neues KI-Start-up von Jajah-Gründer Daniel Mattes". Futurezone. 22 November 2015. Retrieved 2015-11-22.