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|Divisors||1, 7, 49|
Forty-nine is the square of seven
The sum of the digits of the square of 49 (2401) is the square root of 49.
49 is the first square where the digits are squares. In this case 4 and 9 are squares.
Along with the number that immediately derives from it, 77, the only number under 3 digits not having its home prime known (as of late 2010).
The fraction 1/ is a repeating decimal with a period of 42:
- 1/ = 0.0204081632 6530612244 8979591836 7346938775 51 (42 digits repeat)
There are 42 (note that this number is the period) positive integers that are less than 49 and coprime to 49. Multiplying 020408163265306122448979591836734693877551 by each of these integers results in a cyclic permutation of the original number:
- 020408163265306122448979591836734693877551 × 2 = 040816326530612244897959183673469387755102
- 020408163265306122448979591836734693877551 × 3 = 061224489795918367346938775510204081632653
- 020408163265306122448979591836734693877551 × 4 = 081632653061224489795918367346938775510204
The repeating number can be obtained from 02 and repetition of doubles placed at two places to the right:
02 04 08 16 32 64 128 256 512 1024 2048 + ... ---------------------- 020408163265306122448979591836734693877551...0204081632...
- The atomic number of indium.
- During the Manhattan Project, plutonium was also often referred to, simply, as "49". Number 4 was for the last digit in 94 (atomic number of plutonium) and 9 for the last digit in Pu-239, the weapon-grade fissile isotope used in nuclear bombs.
- Messier object M49, a magnitude 10.0 galaxy in the constellation Virgo.
- The New General Catalogue object NGC 49, a spiral galaxy in the constellation Cetus.
- In Judaism, the number of days of the Counting of the Omer
- The number of days and night Siddhartha Gautama spent meditating as a holy man
- In Buddhism, 49 days is one of the lengths of the intermediate state (bardo)
- 49er, a member of the NFL's San Francisco 49ers.
- Arsenal had a 49 game unbeaten run between May 2003 to October 2004 until they lost to Manchester United which is a national record in English football.
- Rocky Marciano ended his career as the only heavyweight champion with a perfect record–49 wins in 49 professional bouts, with 43 knockouts.
- "49 Bye-Byes", a song on the self-titled album Crosby Stills and Nash
- "Days of 49", a Bob Dylan song on the album Self Portrait
- 49:00... Of Your Time/Life is a one-track solo album by Paul Westerberg.
- In Blues music lore, it was at the junction of US Highway 49 and 61 in Clarksdale, Mississippi, that legendary bluesman Robert Johnson sold his soul to the devil in return for fame and success. In later years Howlin' Wolf immortalized the road in the song “Highway 49”, originally written by Big Joe Williams.
In other fields
- HP-49 series is a Hewlett Packard calculator
- 49er, one who participated in the 1849 California Gold Rush.
- The code for international direct dial phone calls to Germany
- In the title of Thomas Pynchon's novel The Crying of Lot 49
- In the title of the movies Ladder 49 and 49 Up
- A 49 is a party after a powwow or any gathering of American Indians, held by the participants. It is also type of song that is sung on such occasions. A 49 is typically held in an isolated place and features drumming and singing.
- 49th parallel between Canada and the USA
- Japanese GS1 country code
- The number of the French department Maine-et-Loire
- "Sloane's A000931 : Padovan sequence". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30.
- Hammel, E.F. (2000). "The taming of "49" — Big Science in little time. Recollections of Edward F. Hammel, pp. 2-9. In: Cooper N.G. Ed. (2000). Challenges in Plutonium Science" (PDF). Los Alamos Science. 26 (1): 2–9.
- Hecker, S.S. (2000). "Plutonium: an historical overview. In: Challenges in Plutonium Science". Los Alamos Science. 26 (1): 1–2.
- "Forty-nine dance". Encyclopedia Britannica. Retrieved May 25, 2018.