50 (number)

← 49 50 51 →
← 50 51 52 53 54 55 56 57 58 59 → List of numbers — Integers ← 0 10 20 30 40 50 60 70 80 90 →
Cardinal	fifty
Ordinal	50th (fiftieth)
Numeral system	quinquagesimal
Factorization	2 × 5^2
Divisors	1, 2, 5, 10, 25, 50
Roman numeral	L
Unicode symbol(s)	ↆ
Binary	1100102
Ternary	12123
Quaternary	3024
Quinary	2005
Senary	1226
Octal	628
Duodecimal	4212
Hexadecimal	3216
Vigesimal	2A20
Base 36	1E36

100

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, and the sum of four squares, 50 = 6² + 3² + 2² + 1². It is a Harshad number.^[2]

There is no solution to the equation φ(x) = 50, making 50 a nontotient.^[3] Nor is there a solution to the equation x − φ(x) = 50, making 50 a Nonients.^[4]

The aliquot sum of 50 is 42 and its aliquot sequence is (50,43,1,0). Fifty is itself the aliquot sum of 40 and 94.

In science

• The atomic number of tin
• The fifth magic number in nuclear physics
• The percent of genetic overlap of a full sibling, a parent and offspring.^[5]

In religion

• In Kabbalah, there are 50 Gates of Wisdom (or Understanding) and 50 Gates of Impurity
• The traditional number of years in a jubilee period.^[6]

In sports

• 50 goals in 50 games is a milestone achievement in the NHL, first set by Maurice "Rocket" Richard in the 1944-45 season.
• The jersey number 50 has been retired by a number of North American sports teams in honor of past playing greats or other figures.
  • In Major League Baseball:
    • The Los Angeles Angels of Anaheim, for coach Jimmie Reese, who served with the team when it was known as the California Angels.
  • In the NBA:
    • The San Antonio Spurs, for Hall of Famer David Robinson.
  • In the NFL:
    • The New York Giants, for Hall of Famer Ken Strong.
  • No NHL team has retired the number, which is not frequently issued.
• The jersey number 50 has also been retired by the men's basketball program of the University of North Carolina for Tyler Hansbrough.
• In cricket one day internationals go for 50 overs.

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^[7]
• 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.
• In the 1994 action movie Speed, which depicts a Los Angeles cop (Keanu Reeves), who must rescue civilians on a bus that has a bomb rigged to it which will detonate if the bus's speed drops below 50 mph.

References

1. de Koninck, J.M. (2009). Those fascinating numbers. AMS Bookstore. p. 18. ISBN 0-8218-4807-0.
2. "Sloane's A005349 : Niven (or Harshad) numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30.
3. "Sloane's A005277 : Nonients". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30.
4. "Sloane's A005278 : Noncotients". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-30.
5. Adkison, Linda (2011). Elsevier's Integrated Review Genetics. p. 42.
6. Leviticus 25:10
7. 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.