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This article is about the number. For the year 50 AD, see 50
. For other uses of 50, see 50 (disambiguation)
50 (fifty) is the natural number following 49 and preceding 51.
In mathematics 
Fifty is the smallest number that is the sum of two non-zero square numbers in two distinct ways: 50 = 12 + 72 = 52 + 52. It is also the sum of three squares, 50 = 32 + 42 + 52. It is a Harshad number.
There is no solution to the equation φ(x) = 50, making 50 a nontotient. Nor is there a solution to the equation x − φ(x) = 50, making 50 a noncototient.
The aliquot sum of 50 is 43 and its aliquot sequence is (50,43,1,0). Fifty is itself the aliquot sum of 40 and 94.
In science 
In religion 
In sports 
In other fields 
- There are 50 states in the United States of America. The TV show Hawaii Five-O and its reimagined version, Hawaii Five-0, are so called because Hawaii is the last (50th) of the states to officially become a state.
- 5-O (Five-Oh) - Slang for police officers and/or a warning that police are approaching. Derived from the television show Hawaii Five-O
- A calibre of ammunition (0.50 inches: see .50 BMG)
- In millimeters, the focal length of the normal lens in 35 mm photography
- The percentage (50%) equivalent to one half, so that the phrase "fifty-fifty" commonly expresses something divided equally in two; in business this is often denoted as being the ultimate in equal partnership
- In years of marriage, the gold or "golden" wedding anniversary
- Nickname 50 Cent, a rapper.
- A Canadian brand of beer called 50 Ale created in 1950 by Labatt breweries to commemorate 50 years of partnership. It is a popular brand still sold today.
- The fiftieth pope was Pope Anastasius II.
- The speed limit, in kilometers per hour, of Australian roads with unspecified limits.
- ^ de Koninck, J.M. (2009). Those fascinating numbers. AMS Bookstore. p. 18. ISBN 0-8218-4807-0.
- ^ Leviticus 25:10