42 (number)

← 41 42 43 →
← 40 41 42 43 44 45 46 47 48 49 → List of numbers Integers ← 0 10 20 30 40 50 60 70 80 90 →
Cardinal	forty-two
Ordinal	nd
Factorization	2 · 3 · 7
Divisors	1, 2, 3, 6, 7, 14, 21, 42
Greek numeral	ΜΒ´
Roman numeral	XLII
Unicode symbol(s)
Greek prefix	μβ
Binary	1010102
Ternary	11203
Senary	1106
Octal	528
Duodecimal	3612
Hexadecimal	2A16

42 (forty-two) is the natural number immediately following 41 and directly preceding 43. The number has received considerable attention in popular culture as a result of its central appearance in The Hitchhiker's Guide to the Galaxy as the "Answer to the Ultimate Question of Life, the Universe, and Everything".

Mathematics

The 3 × 3 × 3 magic cube with rows summing to 42.

• 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 3 cubes whose sum of values is 42.
• Forty-two is a pronic number and an abundant number; its prime factorization 2 · 3 · 7 makes it the second sphenic number and also the second of the form { 2 · 3 · r }. As with all sphenic numbers of this form, the aliquot sum is abundant by 12. 42 is also the second sphenic number to be bracketed by twin primes; 30 is also a pronic number and also rests between two primes. 42 has a 14 member aliquot sequence 42, 54, 66, 78, 90, 144, 259, 45, 33, 15, 9, 4, 3, 1, 0 and is itself part of the aliquot sequence commencing with the first sphenic number 30. Further, 42 is the 10th member of the 3-aliquot tree.
• 42 is the product of the first three terms of Sylvester's sequence; like the first five such numbers it is also a primary pseudoperfect number.
• It is a Catalan number. 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 the reciprocal of the sixth Bernoulli number.
• It is conjectured to be the scaling factor in the leading order term of the "sixth moment of the Riemann zeta function". In particular, Conrey & Ghosh have conjectured

  ${1 \over T}\int _{0}^{T}\left|\zeta \left({1 \over 2}+it\right)\right|^{6}\,dt\sim {42 \over 9!}\prod _{p}\left\{1-{1 \over p}\right\}^{4}\left(1+{4 \over p}+{1 \over p^{2}}\right)\log ^{9}T,$

  where the infinite product is over all prime numbers, p.

• It is the third pentadecagonal number. It is a meandric number and an open meandric number.
• 42 is a Størmer number.
• 42 is a perfect score on the USA Math Olympiad (USAMO) and International Mathematical Olympiad (IMO).
• In base 10, this number is a Harshad number and a self number, while it is a repdigit in base 4 (as 222).

Science

• The atomic number of molybdenum.
• The angle in degrees for which a rainbow appears or 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, evacuate it (remove the air), and then just fall through. 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. Remarkably, even if the tube does not pass through the exact center of the Earth, the time for a journey powered entirely by gravity (also known as Gravity train) always works out to be 42 minutes, as long as the tube remains friction-free, as while gravity's force would be lessened, so would the distance traveled at an equal rate. (The same idea was proposed, without calculation by Lewis Carroll in 1893 in Sylvie and Bruno Concluded.)

Technology

• Magic numbers used by programmers:
  • The glyph, or character, corresponding to the number 42 in the ASCII character set, is *, the asterisk, commonly known as the wildcard character.
  • In the TIFF image file format, the second 16-bit word of every file is 42, which is used together with the first word to indicate byte order.
  • In the reiser4 file system, 42 is the inode number of the root directory.
  • In the military IRIG 106 Chapter 10 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.
• 42 is the result given by the web search engines Google, Wolfram Alpha and Bing when the query "the answer to life the universe and everything" is entered as a search.
• The type 42 vacuum tube was one of the most popular audio output amplifiers of the 1930s.
• One of Advanced Micro Devices' Overlocking CPU was named Phenom 42, with the number being partially from the book The Hitchhikers Guide to the Galaxy.
• Microsoft's Windows 3.x logo has 42 little squares forming its left side trail.
• Facebook chat has a special emoticon that can be used on its chat feature. When a person types ":42:" on it, the number appears white in a red box. This is not possible with any other number.
• Tiling a plane using regular hexagons, which is honeycomb in appearance, is approximated in a topological sense to an accuracy of better than 1% using a stretcher bond brick pattern with bricks of 42 squares (6 by 7).

Astronomy

• Messier object M42, a magnitude 5.0 diffuse nebula in the constellation Orion, also known as the Orion Nebula
• The New General Catalogue object NGC 42, a spiral galaxy in the constellation Pegasus
• In January 2004, asteroid 2001 DA42 was given the permanent name 25924 Douglasadams, for the author Douglas Adams who popularized the number 42 and died in 2001. Brian G. Marsden, the director of the Minor Planet Center and the secretary for the naming committee, remarked that, with even his initials in the provisional designation, "This was sort of made for him, wasn't it?"

Religion

• In Japanese culture, the number 42 is considered unlucky because the numerals when pronounced separately — "shi ni" (four two) — sound like the phrase, "unto death".
• There are 42 principles of Ma'at, the Ancient Egyptian personification of physical and moral law, order, and truth. In the judgement scene described in the Egyptian and the Book of the Coming/Going Forth by Day (the Book of the Dead (which evolved from the Coffin Texts and the Pyramid Texts)), there are 42 gods and goddesses of Egypt, personifying the principles of Ma'at, who ask questions of the departed, while Thoth records the answers, and the deceased's heart is weighed against the feather of Truth (Ma'at). These 42 correspond to the 42 Nomes (Governmental Units) of Egypt. If the departed successfully answers all 42, s/he becomes an Osiris.
• 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"). 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 (see further up this page) 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.
• 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 Dr. 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.
• 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 summarise Anglican doctrine, as it now existed under the reign of Edward VI.

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", and is calculated by an enormous supercomputer over a period of 7.5 million years to be 42. Unfortunately no one knows what the question is. Thus, to calculate the Ultimate Question, a special computer the size of a small planet and using organic components was created and named "Earth". 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 examines Adams' choice of the number 42 and also contains a compendium of some instances of the number in science, popular culture, and humour.

Works of Lewis Carroll

Lewis Carroll made repeated use of this number in his writings.

Examples of Carroll's use of 42:

• Alice's Adventures in Wonderland has 42 illustrations.
• 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 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."
• 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 - gives a total of 37,044 days. With the further (textually unconfirmed) assumption that both Queens were born on the same day their combined age becomes 74,088 days, which is 42 x 42 x 42. Some commentators have asserted that this is deliberate on Carroll's part.

Music

• Level 42 is an English pop/rock music band.
• "42" is one of the tracks on Coldplay's 2008 album Viva la Vida or Death and All His Friends.
• Strigaskór nr. 42 is an Icelandic band.
• "42" is the title of a song by Philadelphia based jam/electronica band Disco Biscuits.
• "Forty-Two" is the title of a song from The Afters' 2008 album Never Going Back To OK.
• "42" is the title of a song by Swedish powerpop/rock band Roomie.
• "Blue 42" is a song by the metalcore band Haste The Day.
• "Forty-two" is the first album by Dutch 'instrumetal' band Vogon Poetry.

Television and film

• The Kumars at No. 42 television series. In 2003, Sanjeev Bhaskar hosted a BBC show nominating The Hitchhiker's Guide to the Galaxy as Britain's Best Loved Book.
• 42 is one of The Numbers - 4, 8, 15, 16, 23, and 42 - featured in Lost. It is also the number tied to the character "Kwon".
• A made for TV movie 42: Forty Two Up - an installment in a series of documentaries wherein the director revisits the same group of British-born individuals every 7 years.
• "42" is an episode of Doctor Who, set in real time lasting approximately 42 minutes.
• In an episode of "Stargate Atlantis" it is revealed that Rodney Mckay's password is made up of the birth years of several notable minds throughout history, and ends with the number 42. The character John Sheppard reveals that the number is the ultimate answer to life, the universe and everything, to the confusion of his alien companion.
• In the episode "Human" from Stargate Universe, the key to a code appears to be the number 46. Upon seeing this, Daniel Jackson exclaims: "Well, it's not the ultimate answer to life, the universe and everything. That's forty two. Hitchhiker's Guide to the Galaxy."
• On the game show "Jeopardy!", "Watson" the IBM supercomputer, has 42 "threads" in its avatar.
• On the "Unusuals" tv-show there's an episode called "42". Detective Leo Banks recently turned 42. On account of his father, uncle, and grandfather dropping dead at 42, Leo is convinced he'll share their fate. There were 42s all over the episode.

Video games

• 42 Entertainment is the company responsible for several alternate reality games, including I Love Bees, Year Zero, and Why So Serious.
• In Spore, reaching the center of the galaxy yields a powerful item known as the "Staff of Life" which has a limited 42 uses. It also grants the player an achievement titled "42".
• In Fable II, the last in a series of ancient artifacts the player can find says "Now just think of the number 42."
• In Valve Corporation's Left 4 Dead 2, 42 is the number of Moustachios that must be shot in the Dark Carnival campaign's Whack-a-Mole style mini-game in order to unlock the STACH WACKER achievement.
• In Destroy All Humans!, the player goes into a parody of Area 51 called Area 42.
• In Steins;Gate a 42 inch direct view CRT television serves as the lifter needed to successfully use a prototype time machine.
• In Earthworm Jim 2, in the game show in the level The Villi People, one of the questions is "What is the meaning of life?", and the answer is "42".

Sports

Jackie Robinson in his now-retired number 42 jersey.

• 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, is currently still using it.
• The jersey number of basketball Hall of Famer and one of the 50 Greatest Players in NBA History James Worthy, small forward for the Los Angeles Lakers, who retired his jersey number in 1995.
• The jersey number of football Hall of Famer, Ronnie Lott, safety for the San Francisco 49ers, who retired his jersey number in 2003.
• The jersey number of Chicago Bears legend Sid Luckman, which was retired by the Bears.
• The jersey number of Pat Tillman, which was retired on November 13, 2004 by Arizona State University.
• The number of laws of cricket
• The number of kilometers in a marathon.
• Rule 42 is the historic name of a Gaelic Athletic Association rule (now codified in Rule 5.1 and Rule 44) that in practice prohibits the playing of "foreign sports" (generally association football and the rugby codes) at GAA grounds.
• 42 is the number of a NASCAR car owned by Earnhardt Ganassi Racing. It is currently being driven by former F1 star and Indy 500 champion Juan Pablo Montoya.

Other fields

• +42 is the historic Country calling code for the former country of Czechoslovakia
• There are 42 US gallons in a barrel of oil.
• Tower 42 is a skyscraper in the City of London, formerly known as the NatWest Tower.
• The name of a Texan trick-taking game played with dominoes (see 42 (dominoes)).
• The number of spots (or pips, circular patches or pits) on a pair of standard six-sided dice.
• In New York City, 42nd Street is a main and very popular two-way thoroughfare. Landmarks on it include the Chrysler Building, Grand Central Terminal, the main branch of the New York Public Library, and Times Square. The New York City street is also the setting for a movie by the same name (which also gave fame to its eponymous title song), and which later inspired a musical adaptation, 42nd Street.
• Popular gadget magazine Stuff did not produce an issue numbered 42, in honor of The Hitchhiker's Guide to the Galaxy, instead, the 41st issue was followed by the 43rd.
• The designation within ISO/IEC JTC1/SC7 of its working group on Architecture was chosen to be "WG 42" because architecture is the answer to "Life, the Universe and Everything", skipping over designations 26 through 41.
• Fictional comic book superhero Miles Morales is bitten by a genetically altered spider with a red 42 marked on its abdomen. Morales later assumes the role of Spider-Man as a result of the bite and following the death of Peter Parker in the Ultimate Marvel universe from Marvel Comics. Morales also wins a coveted spot in a prestigious charter school after his number (42) is chosen during a lottery.

Other languages

Language	Translation
Afrikaans	twee-en-veertig
Arabic	إثنان و أربعون
Basque	Berrogeita bi
Bulgarian	четиридесет и две
Catalan	quaranta-dos
Chinese	四十二
Chuvash	хĕрĕх иккĕ (IIXXXX)
Croatian	četrdesetdva
Czech	čtyřicet dva
Danish	toogfyrre
Dutch	tweeënveertig
Esperanto	kvardek du
Estonian	nelikümmend kaks
Finnish	neljäkymmentäkaksi
Filipino	apatnapu't dalawa
French	quarante-deux
Frisian	twaenfjirtich
Georgian	ორმოცდაორი [ormocdaori]
German	zweiundvierzig
Greek	σαράντα δύο
Hebrew	ארבעים ושתיים (arbayim u-shtayim)
Hindi	बयालीस, ४२
Hungarian	negyvenkettő
Icelandic	fjörutíu og tveir
Indonesian	empat puluh dua
Irish	daichead ceathar
Italian	quarantadue
Japanese	四十二 (よんじゅうに)
Kazakh	Қырық екі
Korean	사십이 (마흔둘)
Latvian	četrdesmit divi
Lietuvių	keturiasdešimt du
Lojban	vore
Luxembourgish	zweeavéierzeg
Macedonian	четириесет и два
Malayalam	naalpathi randu
Maltese	tnejn u erbghin
Marathi	bechalis
Mongolian	дөчин хоёр
Norwegian	førtito
Persian	چهل و دو
Polish	czterdzieści dwa
Portuguese	quarenta e dois
Romanian	patruzeci și doi
Russian	сорок два
Serbian	четрдесет и два (alt. четрдесет два)
Sinhala	හතලිස් දෙක (Hathalis Deka)
Slovene	dvainštirideset
Slovak	štyridsaťdva
Somali	laba iyo afartan
Spanish	cuarenta y dos
Swedish	fyrtiotvå
Tagalog	apatnapu't dalawa
Tamil	நாற்பத்திரண்டு (Narpatti Errundu)
Thai	สี่สิบสอง
Turkish	kırk iki
Ukrainian	Сорок два
Urdu	دو چالیس
Vietnamese	bốn mươi hai
Welsh	pedwar-deg-dau, dau-ar-ddeugain