50 (number)

This article discusses the number fifty. For the year 50 CE, see 50. For other uses of 50, see 50 (disambiguation)

50 (fifty) is the integer following 49 and preceding 51.

In mathematics

Fifty is the smallest number that can be written as the sum of two squares 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

• The atomic number of tin
• The fifth magic number in physics

Astronomy

• Messier object M50, a magnitude 7.0 open cluster in the constellation Monoceros
• The New General Catalogue object NGC 50, a spiral galaxy in the constellation Cetus
• The Saros number of the solar eclipse series which began on 1201 February 11 BC and ended on 97 April 1. The duration of Saros series 50 was 1298.1 years, and it contained 73 solar eclipses.
• The Saros number of the lunar eclipse series which began on 1134 B.C. July 3 and ended on 164 August 20. The duration of Saros series 50 was 1298.1 years, and it contained 73 lunar eclipses.

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

In sports

• Los Angeles Angels coach Jimmie Reese’s retired uniform #50
• New York Giants Ken Strong, retired NFL uniform #50
• David Robinson, San Antonio Spurs retired NBA uniform #50
• Weddington Wildcats Danny O'Toole Football Uniform #50
• Emeka Okafor of the Charlotte Bobcats wears #50.
• Paul Phongsavan of the Annandale Atoms wears #50

In other fields

Fifty is:

• The TV show Hawaii Five-O is so called because Hawaii is the 50th state
• A gentleman's club in London
• A calibre of ammunition (0.50 inches: see .50 BMG)
• In millimeters, the focal length of the normal lens in 35mm 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.
• The number of chapters in the book of Genesis
• Kennedy Half Dollar (50 cents)
• Roman Numeral: L
• President Ulysses S. Grant is on the U.S. $50 bill
• “Fifty Degrees Below” book by Kim Stanley Robinson
• “50 Ways to Leave Your Lover” song by Paul Simon
• "50 First Dates" movie directed by Peter Segal
• Fabulous 50s, a nickname for the fifties decade
• 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.
• A 1999 Warren Miller film showcasing skiers and snowboarders at various exotic locations.
• The number of the French department Manche

Historical years

50 A.D., 50 B.C., 1950, 2050, etc.