50 (number)

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

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 answer to the equation φ(x) = 50, making 50 a nontotient. Nor is there an answer to the equation x - φ(x) = 50, making 50 a noncototient.

Other fields

Fifty is also:

• The atomic number of tin.
• The fifth Magic number.
• The traditional number of years in a default jubilee period.
• The number of states in the USA (since 1959, still true in 2004).
• A calibre of ammunition (0.50 inches: see .50 BMG)
• In millimeters, the focal length of the normal lens in 35mm photography.
• the percentage equivalent to one half, so that the phrase "fifty-fifty" commonly expresses something divided equally in half, or an event of probability one half
• In U.S. dollars, the denomination of the Federal Reserve note with Ulysses S. Grant's portrait, the denomination of the savings bond with George Washington's portrait, and the denomination of treasury bonds with Thomas Jefferson's portrait.
• In cents of the U.S. dollar, the denomination of the coin with John F. Kennedy's portrait.
• In years of marriage, the gold or "golden" wedding anniversary.
• part of the name of 50 Cent, a rapper.
• One of the years: AD 50, 50 BC, or (for example) 1950.

es:Cincuenta ia:50 it:Cinquanta ja:50 sl:50 (število) sv:50 (tal) zh:50