# 47 (number)

47 (forty-seven) is the natural number following 46 and preceding 48. It is a prime number, and appears in popular culture as the adopted favorite number of Pomona College and an obsession of the hip hop collective Pro Era.

 ← 46 47 48 →
Cardinalforty-seven
Ordinal47th
(forty-seventh)
Factorizationprime
Prime15th
Divisors1, 47
Greek numeralΜΖ´
Roman numeralXLVII
Binary1011112
Ternary12023
Octal578
Duodecimal3B12

## In mathematics

Forty-seven is the fifteenth prime number, a safe prime,[1] the thirteenth supersingular prime,[2] and the sixth Lucas prime.[3] Forty-seven is a highly cototient number.[4] It is an Eisenstein prime with no imaginary part and real part of the form 3n − 1.

It is a Lucas number. It is also a Keith number because its digits appear as successive terms earlier in the series of Lucas numbers: 2, 1, 3, 4, 7, 11, 18, 29, 47, ...[5]

Forty-seven is a strictly non-palindromic number.[6]

Its representation in binary being 00101111, 47 is a prime Thabit number, and as such is related to the pair of amicable numbers {17296, 18416}.

Forty-seven is a Carol number.[7]

## In popular culture

### Pomona College

The number 47 has historical implications to Pomona College, a liberal arts college in Claremont, California, and has been incorporated into various aspects of campus life.[10][11]

The tradition began in the summer of 1964, when two students, Laurie Mets and Bruce Elgin, conducted a research project seeking to find out whether the number occurs more often in nature than would be expected by chance. They documented a number of 47 sightings, and professor Donald Bentley produced a false mathematical proof that 47 was equal to all other integers. 47 subsequently became a meme among the class, which spread once the academic year began and snowballed over time.[12]

Notable 47 sightings include the fact that Pomona is located off of exit 47 of Interstate 10, and the fact that the largest residential building on campus, Mudd-Blaisdell (formally Florence Carrier Blaisdell and Della Mullock Mudd Hall, a title with 47 characters), was completed in 1947 and contains a staircase with 47 balusters.[12]

Many Pomona alumni have deliberately inserted 47 references into their work. Pomona hosts a community service-oriented celebration every April 7 (often abbreviated 4/7 in the U.S.).[13] In the early 2010s, the college's clock tower was set up to chime on the 47th minute of the hour.[14][15]

### Star Trek

Joe Menosky graduated from Pomona College in 1979 and went on to become one of the story writers of Star Trek: The Next Generation. Menosky "infected" other Star Trek writers with an enthusiasm for the number 47.[16] As a result, 47, its reverse 74, its multiples, or combinations of 47 occur in a large number of episodes of the program and its spin-offs Star Trek: Deep Space Nine, Star Trek: Voyager, and Star Trek: Enterprise,[17][18] usually in the form of dialogue, on-screen labels, or computer screens. For example:

• In the TNG episode "Darmok", the computer of the Enterprise reports to have found 47 occurrences of the word "Darmok" in its database.
• In Star Trek Generations, Scotty manages to beam up only 47 El-Aurians before their ship is destroyed by the energy ribbon.
• In the Voyager episode "Parallax", we learn that the Emergency Medical Holographic Channel is 47 and that the EMH has the experience of 47 individual medical officers.
• In the Voyager episode "Non Sequitur", Harry Kim lives in apartment 4-G, G being the seventh letter of the alphabet. The intentionality of this reference to 47 was confirmed by Brannon Braga, the writer of that episode.[19]
• In the 2009 film Star Trek, the Enterprise was built in Sector 47 of the Riverside Shipyards, and 47 Klingon ships are said to have been destroyed by Nero's ship, the Narada.

J. J. Abrams, who produced and directed Star Trek, frequently uses the number 47 in his productions, including episodes of his TV series Fringe. In the Season 1 episode "Bad Dreams", aired shortly before the release of Star Trek in theaters, Nick Lane's bulletin board features a large centrally-located sheet of paper with only the number 47 in huge typeface. It recurs in the series: for example, 47 minutes being the maximum amount of time for a time chamber in the series to last, and there being exactly 47 shapeshifters. J.J. Abrams continues to incorporate 47 into movies and series he produces and directs. The final sequence of Mission: Impossible – Ghost Protocol takes place on Pier 47. There are many 47s in Fringe, Alias, and Revolution. In Star Wars: The Force Awakens, the thermal oscillator is located in Precinct 47. In the Season 1 episode "Soul Train" of the series Revolution, the characters are involved with an old train engine where the engine number happens to be 47.[20] When asked about the significance of the number, Rick Berman once joked, "47 is 42, corrected for inflation" referring to 42 being "the answer to the Ultimate Question of Life, the Universe, and Everything" according to The Hitchhiker's Guide to the Galaxy by Douglas Adams.

### Claymore

Claymore is a manga and anime following a group of monster-slaying women dubbed "Claymores", operating under a secretive Organization. In each generation of Claymores, 47 are individually ranked, with No. 1 being the strongest and No. 47 being labeled the weakest. Clare, the series' main protagonist, is herself No. 47 of her generation. Clarice, also No. 47 of the following and final generation, proves instrumental in the series' ending.

### 2012 U.S. presidential election

During the 2012 election, Republican candidate Mitt Romney made a comment claiming that 47 percent of Americans do not pay any income tax.[21][22] Since the comment potentially sabotaged his chances of winning the election against Barack Obama, the term "47 percent" has been used by critics to describe actions that could potentially damage a political candidate. For example, during the 2016 election, Hillary Clinton's speech labeling half Donald Trump's supporters as "deplorable" was compared by critics to Romney's 47 percent speech.[23][24][25]

### Pro Era

The Brooklyn-based hip hop collective Pro Era and its late co-founder Jamal Dewar, better known by his stage name Capital Steez, have made references to the number 47 in various songs by members of the group. The design of one of Pro Era's logos is the number 47 with its digits joined together.[26] The origins of the group's connection with the number can be linked to the production of Capital Steez's 2012 debut mixtape AmeriKKKan Korruption. The rapper was heavily fixated with the number during that time; he felt that 47 was a perfect expression of balance in the world, representing the tension between the heart and the brain (the fourth and seventh chakra, respectively).[27]

## References

1. ^ "Sloane's A005385 : Safe primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30.
2. ^ "Sloane's A002267 : The 15 supersingular primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30.
3. ^ "Sloane's A005479 : Prime Lucas numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30.
4. ^ "Sloane's A100827 : Highly cototient numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30.
5. ^ "Sloane's A007629 : Repfigit (REPetitive FIbonacci-like diGIT) numbers (or Keith numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30.
6. ^ "Sloane's A016038 : Strictly non-palindromic numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30.
7. ^ "Sloane's A093112 : a(n) = (2^n-1)^2 - 2". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30.
8. ^ [1]
9. ^ The NGC / IC Project - Home of the Historically Corrected New General Catalogue (HCNGC) since 1993
10. ^ Lipka, Sara (11 February 2005). "Pomona's Prime Number". The Chronicle of Higher Education. Retrieved 7 April 2020.
11. ^ "1964". Pomona College Timeline. Pomona College. Retrieved 7 April 2020.
12. ^ a b Dolinar, Sarah. "The Mystery of 47". Pomona College Magazine (Fall 2000). Pomona College. Retrieved 7 April 2020.
13. ^ "4/7 Celebration of Sagehen Impact". Pomona College. Archived from the original on July 31, 2019. Retrieved 7 April 2019.
14. ^ Rowan, Brendan (November 5, 2010). "Clock Tower Bell Set to Chime On the 47th Minute". The Student Life. Archived from the original on July 31, 2019. Retrieved 7 April 2019.
15. ^ "Tower's bell ringing again at Pomona College". Los Angeles Daily News. November 7, 2010. Archived from the original on July 31, 2019. Retrieved 7 April 2019.
16. ^ "Stardate 47". Pomona College (via Internet Archive). Archived from the original on September 1, 2006. Retrieved 2010-05-17.
17. ^ "The Mystique of 47". Pomona College (via Internet Archive). Archived from the original on 2006-09-01. Retrieved 2010-05-16.
18. ^ "Starbase Pomona". Pomona College (via Internet Archive). Archived from the original on September 1, 2006. Retrieved 2010-05-17.
19. ^ schlock.net: A letter from Brannon Braga
20. ^ Roco. "Revolution Observations: 1.05 Soul Train". Seriable.com. Retrieved 28 April 2013.
21. ^ Dixon, Kim (October 19, 2012). "Analysis: "47 percent" lament belies Republican tax credit support". Reuters. Retrieved September 11, 2016.
22. ^ Cillizza, Chris (March 4, 2013). "Why Mitt Romney's "47 percent" comment was so bad". Washington Post. Retrieved September 11, 2016.
23. ^ Chozick, Amy (September 10, 2016). "Hillary Clinton Calls Many Trump Backers 'Deplorables,' and G.O.P. Pounces". The New York Times. Retrieved September 11, 2016.
24. ^ Blake, Aaron (September 10, 2016). "Did Hillary Clinton just make her own '47 percent' gaffe?". Washington Post. Retrieved September 11, 2016.
25. ^ Mehta, Seema (September 10, 2016). "Campaign 2016 updates: Republicans pounce upon Clinton 'deplorables' remark. She apologizes. Sort of". Los Angeles Times. Retrieved September 11, 2016.
26. ^ "Controversial symbol shows up along Avenue K in Midwood". News 12 Brooklyn. News 12 Brooklyn. 24 March 2014. Archived from the original on 2014-07-06. Retrieved 21 April 2014.
27. ^ Rosenberg, Eli (November 26, 2013). "Capital Steez: King Capital". The Fader. Archived from the original on August 30, 2016. Retrieved August 30, 2016.