42 (number) explained

Number:	42
Divisor:	1, 2, 3, 6, 7, 14, 21, 42

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

Mathematics

42 is a pronic number,^[1] an abundant number^[2] as well as a highly abundant number,^[3] a practical number,^[4] an admirable number,^[5] and a Catalan number.^[6]

The 42-sided tetracontadigon is the largest such regular polygon that can only tile a vertex alongside other regular polygons, without tiling the plane.^{[7] [8] [9]}

42 is the only known

k that is equal to the number of sets of four distinct positive integers (a,b,c,d) — each less than k — such that ab - cd, ac - bd and ad - bc are all multiples of k . Whether there are other values remains an open question.^[10]

42 is the magic constant of the smallest non-trivial magic cube, a

3 x 3 x 3 cube with entries of 1 through 27, where every row, column, corridor, and diagonal passing through the center sums to forty-two.^{[11] [12]}

42 can be expressed as the sum of three cubes:$$80,435,758,145,817,515^3\; +\; 12,602,123,297,335,631^3\; +\; (-80,538,738,812,075,974)^3\; =\; 42.$$^[13]

Technology

• Magic numbers used by programmers:
  • In TIFF (Tag Image File Format), the second 16-bit word of every file is 42, "an arbitrary but carefully chosen number that further identifies the file as a TIFF file".
  • In the reiser4 file system, 42 is the inode number of the root directory.
  • In the military IRIG 106 Chapter 10^[14] data recording standard, the hex value 0x464F52545974776F (ASCII "FORTYtwo") is used as a magic number to identify directory blocks.
  • The GNU C Library, a set of standard routines available for use in computer programming, contains a function—memfrob—which performs an XOR combination of a given variable and the binary pattern 00101010 (42) as an XOR cipher.
  • The password expiration policy for a Microsoft Windows domain defaults to 42 days.^[15]
  • The nonce of the first ethereum blockchain block is the hex value 0x42^[16]

• Abrahamic religions
  • In Judaism, by some traditions the Torah scroll is written with no fewer than 42 lines per column, based on the journeys of Israel.^[17] In the present day, 42 lines is the most common standard,^[18] 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").^[19] 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. 42 letters make the Ana beKo'ach prayer.^[20]

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"^[21] is 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,, contains 42 chapters. According to, 42 is the street address of Stavromula Beta. In 1994, Adams created the 42 Puzzle, a game based on the number 42. Adams says he picked the number simply as a joke, with no deeper meaning.

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.^[22]

Jackie Robinson

• The jersey number of Jackie Robinson, which is the only number retired by all Major League Baseball teams. Although the number was retired in 1997, Mariano Rivera of the New York Yankees, the last professional baseball player to wear number 42, continued to wear it until he retired at the end of the 2013 season. As of the 2014 season, no player ever again wore the number 42 in Major League Baseball except on Jackie Robinson Day (April 15), when all uniformed personnel (players, managers, coaches, and umpires) wear the number.
  • 42 is a film on the life of American baseball player Jackie Robinson.
  • 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 . The use of 42 within the franchise references Jackie Robinson's use of the number, though many fans incorrectly believed it to be a Hitchhiker's Guide to the Galaxy reference.^[23]

Other

In Japanese culture, the number 42 is considered unlucky because the numerals when pronounced separately—shi ni (four two)—sound like the word "dying",^[24] like the Latin word "mori".

External links

• Web site: Grime. James. 42 and Douglas Adams. Numberphile. Brady Haran. Gerardo Adesso. Phil Moriarty. 2013-04-08. https://web.archive.org/web/20181013132841/http://www.numberphile.com/videos/42.html. 2018-10-13. dead.
• My latest favorite Number: 42, John C. Baez
• The number Forty-two in real life

Notes and References

1. A002378. Oblong (or promic, pronic, or heteromecic) numbers. 2016-05-30.
2. 2024-01-07 .
3. 2024-11-14 .
4. 2024-11-14 .
5. 2024-11-14 .
6. 2016-05-30.
7. Branko . Grünbaum . Branko Grünbaum . Geoffrey . Shepard . G.C. Shephard . Tilings by Regular Polygons . November 1977 . . 50 . 5 . Taylor & Francis, Ltd.. 229–230 . 10.2307/2689529 . 2689529 . 123776612 . 0385.51006 . 0025-570X .
8. Book: Dallas, Elmslie William . Elmslie William Dallas . https://books.google.com/books?id=y4BaAAAAcAAJ&pg=PA134 . The Elements of Plane Practical Geometry . Part II. (VII): Of the Circle, with its Inscribed and Circumscribed Figures − Equal Division and the Construction of Polygons . John W. Parker & Son, West Strand . London . 1855 . 134 .
9. Web site: Jardine . Kevin . Shield - a 3.7.42 tiling . Imperfect Congruence . 2023-01-09 . 3.7.42 as a unit facet in an irregular tiling.
10. Web site: Kevin Brown . Differently Perfect . MathPages .
11. Book: Andrews, William Symes . William Symes Andrews . Magic Squares and Cubes . . 2nd . New York . 1960 . 65 . 10.2307/3603128 . 3603128 . 9780486206585 . 1136401 . 0114763 . 1003.05500 . 121770908 .
12. 2024-01-07 .
13. Booker . Andrew R. . Sutherland . Andrew V. . 2021 . On a question of Mordell . Proceedings of the National Academy of Sciences . 118 . 11 . 2007.01209 . 2021PNAS..11822377B . 10.1073/pnas.2022377118 . 7980389 . 33692126 . free.
14. Web site: Berard . April 2009 . IRIG 106 Telemetry Standard Chapter 10 . live . https://web.archive.org/web/20201112013409/http://www.irig106.org/docs/106-09/chapter10.pdf . Range Commanders Council . 2020-11-12 . U.S. Army White Sands Missile Range, New Mexico . 2010-11-10.
15. Web site: Maximum password age. Microsoft TechNet. 15 January 2014.
16. Web site: Ethereum Blocks #0. Etherscan.
17. Book: Ganzfried . R. Solomon . Friendman . Jen . קסת הסופר. Keset haSofer . 1902. דפוס יוסף מאיר בלייער . Bardejov . First . he,en . 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..
18. Encyclopedia: Joseph . Jacobs . Judah . Eisenstein . Executive Committee of the Editorial Board . Ludwig . Blau . Jewish Encyclopedia . Scroll of the Law (Hebrew, "Sefer Torah") . 12 February 2020 . en . 1906 . "(At the present day the forty-two-lined column is the generally accepted style of the scroll, its length being about 24 inches.)".
19. Web site: In A Beginning...Quantum Cosmology and Kabbalah. 2008-03-14. Joel Primack. Nancy E. Abrams.
20. Web site: The Prayer of the Kabbalist .
21. Web site: Mathematical Fiction: Hitchhiker's Guide to the Galaxy (1979). 30 November 2016. See this website for possible explanations of this seeming error.
22. Web site: November 11, 2011 . 17 amazing Google Easter eggs . November 1, 2022 . CBS News.
23. Web site: Why the number 42 was hidden in plain sight throughout 'Spider-Man: Into the Spider-Verse'. Kim. Renfro. February 26, 2019. November 29, 2019. Insider Inc..
24. Niiya, Brian. Japanese American history: an A-to-Z reference from 1868 to the present. Facts on File, Inc., 1993, p. 352