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 n ...

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 usua ...

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 In mathematics, a harshad number (or Niven number) in a given number base is an integer that is divisible by the sum of its digits when written in that base. Harshad numbers in base are also known as -harshad (or -Niven) numbers. Harshad numbers ...

. 50 is a Stirling number of the first kind:

\left

right Rights are law, legal, social, or ethics, ethical principles of Liberty, freedom or entitlement; that is, rights are the fundamental normative rules about what is allowed of people or owed to people according to some legal system, social convent ...

= 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 nontotient ...

. 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 ...

tin Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...

*The fifth magic number in nuclear physics

In religion

*In

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

, 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 Pentecost (also called Whit Sunday, Whitsunday or Whitsun) is a Christianity, Christian holiday which takes place on the 50th day (the seventh Sunday) after Easter Sunday. It commemorates the descent of the Holy Spirit upon the Apostles in the Ne ...

takes place on the 50th day of the

Easter Season Eastertide (also known as Eastertime or the Easter season) or Paschaltide (also known as Paschaltime or the Paschal season) is a festal season in the liturgical year of Christianity that focuses on celebrating the Resurrection of Jesus Christ. ...

*The Jewish

takes place 50 days after the

Passover Passover, also called Pesach (; ), is a major Jewish holidays, Jewish holiday that celebrates the The Exodus, Biblical story of the Israelites escape from slavery in Ancient Egypt, Egypt, which occurs on the 15th day of the Hebrew calendar, He ...

feast (the holiday of

Shavuoth (''Ḥag HaShavuot'' or ''Shavuos'') , nickname = English: "Feast of Weeks" , observedby = Jews and Samaritans , type = Jewish and Samaritan , begins = 6th day of Sivan (or the Sunday following the 6th day of Sivan i ...

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 Cu ...

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

'', 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 stat ...

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 The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a system converges light, while a negative foca ...

of the normal lens in 35 mm photography * The

percentage In mathematics, a percentage (from la, per centum, "by a hundred") is a number or ratio expressed as a fraction of 100. It is often denoted using the percent sign, "%", although the abbreviations "pct.", "pct" and sometimes "pc" are also us ...

(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