50 (fifty) is the

natural number In mathematics, the natural numbers are those numbers used for counting (as in "there are ''six'' coins on the table") and ordering (as in "this is the ''third'' largest city in the country"). Numbers used for counting are called ''cardinal ...

following 49 and preceding 51.

In mathematics

Fifty is the smallest number that is the sum of two non-zero

square numbers In mathematics, a square number or perfect square is an integer that is the square of an integer; in other words, it is the product of some integer with itself. For example, 9 is a square number, since it equals and can be written as . The us ...

in two distinct ways: 50 = 1² + 7² = 5² + 5². 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. 50 is a Stirling number of the first kind:

\left right = 50

and also a

Narayana number In combinatorics, the Narayana numbers \operatorname(n, k), n \in \mathbb^+, 1 \le k \le n form a triangular array of natural numbers, called the Narayana triangle, that occur in various counting problems. They are named after Canadian mathemati ...

\operatorname(6, 3) = \operatorname(6, 4) = 50

There is no solution to the equation φ(''x'') = 50, making 50 a

nontotient In number theory, a nontotient is a positive integer ''n'' which is not a totient number: it is not in the range of Euler's totient function φ, that is, the equation φ(''x'') = ''n'' has no solution ''x''. In other words, ''n'' is a nontotien ...

. Nor is there a solution to the equation ''x'' − φ(''x'') = 50, making 50 a

noncototient In mathematics, a noncototient is a positive integer ''n'' that cannot be expressed as the difference between a positive integer ''m'' and the number of coprime integers below it. That is, ''m'' − φ(''m'') = ''n'', where � ...

In science

*The

atomic number The atomic number or nuclear charge number (symbol ''Z'') of a chemical element is the charge number of an atomic nucleus. For ordinary nuclei, this is equal to the proton number (''n''p) or the number of protons found in the nucleus of every ...

of tin *The fifth magic number in nuclear physics

In religion

*In

Kabbalah Kabbalah ( he, קַבָּלָה ''Qabbālā'', literally "reception, tradition") is an esoteric method, discipline and school of thought in Jewish mysticism. A traditional Kabbalist is called a Mekubbal ( ''Məqūbbāl'' "receiver"). The defin ...

, there are 50 Gates of Wisdom (or Understanding) and 50 Gates of Impurity *The traditional number of years in a

jubilee A jubilee is a particular anniversary of an event, usually denoting the 25th, 40th, 50th, 60th, and the 70th anniversary. The term is often now used to denote the celebrations associated with the reign of a monarch after a milestone number of y ...

period.Leviticus 25:10 *The Christian Feast of Pentecost takes place on the 50th day of the Easter Season *The Jewish Pentecost takes place 50 days after the

Passover Passover, also called Pesach (; ), is a major Jewish holiday that celebrates the Biblical story of the Israelites escape from slavery in Egypt, which occurs on the 15th day of the Hebrew month of Nisan, the first month of Aviv, or spring. ...

feast (the holiday of Shavuoth).

In sports

* In cricket

one day internationals A One Day International (ODI) is a form of limited overs cricket, played between two teams with international status, in which each team faces a fixed number of overs, currently 50, with the game lasting up to 9 hours. The Cricket World Cup ...

, each side may bat for 50 overs.

In other fields

Fifty is: * There are 50 states in the United States of America. * The TV show ''

Hawaii Five-O Hawaii Five-O or Hawaii Five-0 may refer to: * ''Hawaii Five-0'' (2010 TV series), an American action police procedural television series * ''Hawaii Five-O'' (1968 TV series), an American police procedural drama series produced by CBS Productio ...

'' and its reimagined version, '' Hawaii Five-0'', are so called because

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only state ...

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 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 A wedding anniversary is the anniversary of the date a wedding took place. Couples may take the occasion to celebrate their relationship, either privately or with a larger party. Special celebrations and gifts are often given for particular an ...

* The speed limit, in kilometres per hour, of Australian and Canadian roads with unspecified limits.

References