# 50 (number)

 ← 49 50 51 →
Cardinal fifty
Ordinal 50th
(fiftieth)
Numeral system quinquagesimal
Factorization 2 × 52
Divisors 1, 2, 5, 10, 25, 50
Roman numeral L
Unicode symbol(s)
Binary 1100102
Ternary 12123
Quaternary 3024
Quinary 2005
Senary 1226
Octal 628
Duodecimal 4212
Vigesimal 2A20
Base 36 1E36

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.[1] 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 other fields

Fifty is:

• 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[3]
• A calibre of ammunition (0.50 inches: see .50 BMG)
• In millimetres, 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 kilometres per hour, of Australian and Canadian roads with unspecified limits.
• The number of rings required to transform Sonic to his super form in the Sonic the Hedgehog franchise.

## References

1. de Koninck, J.M. (2009). Those fascinating numbers. AMS Bookstore. p. 18. ISBN 0-8218-4807-0.
2. Leviticus 25:10
3. Karen Rhodes (1 February 1997). Booking Hawaii Five-O: An Episode Guide and Critical History of the 1968–1980 Television Detective Series. McFarland. p. 265. ISBN 978-0-7864-8666-3.