25 (twenty-five) 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 24 and preceding 26.

In mathematics

It is a

square number In mathematics, a square number or perfect square is an integer that is the square (algebra), square of an integer; in other words, it is the multiplication, product of some integer with itself. For example, 9 is a square number, since it equals ...

, being 5² = 5 × 5. It is one of two two-digit numbers whose square and higher powers of the number also ends in the same last two digits, e.g., 25² = 625; the other is 76. It is the smallest square that is also a sum of two (non-zero) squares: 25 = 3² + 4². Hence, it often appears in illustrations of the

Pythagorean theorem In mathematics, the Pythagorean theorem or Pythagoras' theorem is a fundamental relation in Euclidean geometry between the three sides of a right triangle. It states that the area of the square whose side is the hypotenuse (the side opposite t ...

. 25 is the sum of the five consecutive single-digit odd natural numbers 1, 3, 5, 7, and 9. 25 is a

centered octagonal number A centered octagonal number is a centered figurate number that represents an octagon with a dot in the center and all other dots surrounding the center dot in successive octagonal layers.. The centered octagonal numbers are the same as the od ...

, a

centered square number In elementary number theory, a centered square number is a centered figurate number that gives the number of dots in a square with a dot in the center and all other dots surrounding the center dot in successive square layers. That is, each cen ...

, a

centered octahedral number A centered octahedral number or Haüy octahedral number is a figurate number that counts the number of points of a three-dimensional integer lattice that lie inside an octahedron centered at the origin. The same numbers are special cases of the ...

, and an

automorphic number In mathematics, an automorphic number (sometimes referred to as a circular number) is a natural number in a given number base b whose square "ends" in the same digits as the number itself. Definition and properties Given a number base b, a natura ...

. 25 percent (%) is equal to . It is the smallest

decimal The decimal numeral system (also called the base-ten positional numeral system and denary or decanary) is the standard system for denoting integer and non-integer numbers. It is the extension to non-integer numbers of the Hindu–Arabic numeral ...

Friedman number A Friedman number is an integer, which represented in a given numeral system, is the result of a non-trivial expression using all its own digits in combination with any of the four basic arithmetic operators (+, −, ×, ÷), additive inverses, p ...

as it can be expressed by its own digits: 5². It is also a

Cullen number In mathematics, a Cullen number is a member of the integer sequence C_n = n \cdot 2^n + 1 (where n is a natural number). Cullen numbers were first studied by James Cullen in 1905. The numbers are special cases of Proth numbers. Properties In 1 ...

and a vertically symmetrical number. 25 is the smallest

pseudoprime A pseudoprime is a probable prime (an integer that shares a property common to all prime numbers) that is not actually prime. Pseudoprimes are classified according to which property of primes they satisfy. Some sources use the term pseudoprime to ...

satisfying the congruence 7^''n'' = 7 mod ''n''. 25 is the smallest aspiring number — a composite non-

sociable number In mathematics, sociable numbers are numbers whose aliquot sums form a periodic sequence. They are generalizations of the concepts of amicable numbers and perfect numbers. The first two sociable sequences, or sociable chains, were discovered and ...

whose

aliquot sequence In mathematics, an aliquot sequence is a sequence of positive integers in which each term is the sum of the proper divisors of the previous term. If the sequence reaches the number 1, it ends, since the sum of the proper divisors of 1 is 0. Defi ...

does not terminate. According to the

Shapiro inequality In mathematics, the Shapiro inequality is an inequality (mathematics), inequality proposed by Harold S. Shapiro in 1954. Statement of the inequality Suppose n is a natural number and x_1, x_2, \dots, x_n are positive numbers and: * n is even and ...

, 25 is the smallest odd integer ''n'' such that there exist ''x'', ''x'', ..., ''x'' such that :

\sum_^ \frac < \frac

where ''x'' = ''x'', ''x'' = ''x''. Within decimal, one can readily test for divisibility by 25 by seeing if the last two digits of the number match 00, 25, 50, or 75. There are 25 primes under 100.

In science

* The

Standard Model The Standard Model of particle physics is the theory describing three of the four known fundamental forces (electromagnetism, electromagnetic, weak interaction, weak and strong interactions - excluding gravity) in the universe and classifying a ...

of physics features a total of 25

elementary particles In particle physics, an elementary particle or fundamental particle is a subatomic particle that is not composed of other particles. Particles currently thought to be elementary include electrons, the fundamental fermions (quarks, leptons, antiqu ...

: 12

fermions In particle physics, a fermion is a particle that follows Fermi–Dirac statistics. Generally, it has a half-odd-integer spin: spin , spin , etc. In addition, these particles obey the Pauli exclusion principle. Fermions include all quarks and ...

(made of 6

quarks A quark () is a type of elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. All commonly o ...

and 6

leptons In particle physics, a lepton is an elementary particle of half-integer spin (spin ) that does not undergo strong interactions. Two main classes of leptons exist: charged leptons (also known as the electron-like leptons or muons), and neutr ...

) and 13

bosons In particle physics, a boson ( ) is a subatomic particle whose spin quantum number has an integer value (0,1,2 ...). Bosons form one of the two fundamental classes of subatomic particle, the other being fermions, which have odd half-integer spi ...

(made of 12

gauge bosons In particle physics, a gauge boson is a bosonic elementary particle that acts as the force carrier for elementary fermions. Elementary particles, whose interactions are described by a gauge theory, interact with each other by the exchange of gauge ...

and 1

scalar boson A scalar boson is a boson whose spin equals zero. ''Boson'' means that the particle's wave function is symmetric under particle exchange and therefore follows Bose–Einstein statistics. The spin-statistics theorem implies that all bosons have a ...

). *The atomic number of

manganese Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...

. *The average percentage DNA overlap of an individual with their half-sibling, grandparent, grandchild, aunt, uncle, niece, nephew, identical twin cousin (offspring of identical twins), or double cousin.

In religion

*In Ezekiel's vision of a new temple: The number twenty-five is of cardinal importance in Ezekiel's Temple Vision (in the Bible,

Ezekiel Ezekiel (; he, יְחֶזְקֵאל ''Yəḥezqēʾl'' ; in the Septuagint written in grc-koi, Ἰεζεκιήλ ) is the central protagonist of the Book of Ezekiel in the Hebrew Bible. In Judaism, Christianity, and Islam, Ezekiel is acknow ...

chapters 40–48). *In

Islam Islam (; ar, ۘالِإسلَام, , ) is an Abrahamic religions, Abrahamic Monotheism#Islam, monotheistic religion centred primarily around the Quran, a religious text considered by Muslims to be the direct word of God in Islam, God (or ...

, there are 25 prophets mentioned in the Quran.

In sports

* Before 2020, the size of the full roster on a

Major League Baseball Major League Baseball (MLB) is a professional baseball organization and the oldest major professional sports league in the world. MLB is composed of 30 total teams, divided equally between the National League (NL) and the American League (AL), ...

team for most of the season, except for regular-season games on or after September 1, when teams expanded their roster to 40 players. * The size of the playing roster on a

Nippon Professional Baseball or NPB is the highest level of baseball in Japan. Locally, it is often called , meaning ''Professional Baseball''. Outside Japan, it is often just referred to as "Japanese baseball". The roots of the league can be traced back to the formation ...

team for a particular game. Active NPB rosters consist of 28 players, but prior to each game, managers must designate three players who will be ineligible for that game. *In baseball, the number 25 is typically reserved for the best slugger on the team. Examples include

Mark McGwire Mark David McGwire (born October 1, 1963), nicknamed "Big Mac", is an American former professional baseball first baseman who played 16 seasons in Major League Baseball (MLB) from 1986 to 2001 for the Oakland Athletics and the St. Louis Cardi ...

Barry Bonds Barry Lamar Bonds (born July 24, 1964) is an American former professional baseball left fielder who played 22 seasons in Major League Baseball (MLB). Bonds was a member of the Pittsburgh Pirates from 1986 to 1992 and the San Francisco Giants f ...

Jim Thome James Howard Thome (; born August 27, 1970) is an American former professional baseball corner infielder and designated hitter, who played in Major League Baseball (MLB) for 22 seasons (1991–2012). He played for six different teams during th ...

, and

Mark Teixeira Mark Charles Teixeira ( ; born April 11, 1980), nicknamed "Tex", is an American former professional baseball first baseman who played 14 seasons in Major League Baseball (MLB) for the Texas Rangers, Atlanta Braves, Los Angeles Angels of Anahei ...

. *The number of points needed to win a set in volleyball under rally scoring rules (except for the fifth set), so long as the losing team's score is two less than the winning team's score (i.e., if the winning team scores 25 points, the losing team can have no more than 23 points) *In U.S. college football, schools that are members of

NCAA Division I NCAA Division I (D-I) is the highest level of College athletics, intercollegiate athletics sanctioned by the National Collegiate Athletic Association (NCAA) in the United States, which accepts players globally. D-I schools include the major ...

FBS are allowed to provide

athletic scholarship An athletic scholarship is a form of scholarship to attend a college or university or a private high school awarded to an individual based predominantly on his or her ability to play in a sport. Athletic scholarships are common in the United Stat ...

s to a maximum of 25 new football players (i.e., players who were not previously receiving scholarships) each season.

In other fields

Twenty-five is: *Part of the name of the

LSD-25 Lysergic acid diethylamide (LSD), also known colloquially as acid, is a potent psychedelic drug. Effects typically include intensified thoughts, emotions, and sensory perception. At sufficiently high dosages LSD manifests primarily mental, v ...

molecule. *The number of years of marriage marked in a silver

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 minimum age of candidates for election to the

United States House of Representatives The United States House of Representatives, often referred to as the House of Representatives, the U.S. House, or simply the House, is the Lower house, lower chamber of the United States Congress, with the United States Senate, Senate being ...

. "Under 25" provides a common cut-off point for designating

youth Youth is the time of life when one is young. The word, youth, can also mean the time between childhood and adulthood ( maturity), but it can also refer to one's peak, in terms of health or the period of life known as being a young adult. You ...

. *The number of cents in a

quarter A quarter is one-fourth, , 25% or 0.25. Quarter or quarters may refer to: Places * Quarter (urban subdivision), a section or area, usually of a town Placenames * Quarter, South Lanarkshire, a settlement in Scotland * Le Quartier, a settlement i ...

. *The usual

TCP TCP may refer to: Science and technology * Transformer coupled plasma * Tool Center Point, see Robot end effector Computing * Transmission Control Protocol, a fundamental Internet standard * Telephony control protocol, a Bluetooth communication s ...

port for

SMTP The Simple Mail Transfer Protocol (SMTP) is an Internet standard communication protocol for electronic mail transmission. Mail servers and other message transfer agents use SMTP to send and receive mail messages. User-level email clients typical ...

. *The name of the national board game of India (

Pachisi Pachisi (, Hindustani: əˈtʃiːsiː is a cross and circle board game that originated in Ancient India. It is described in the ancient text ''Mahabharata'' under the name of "Pasha". It is played on a board shaped like a symmetrical cross. A ...

— Hindi for 25). *The name of an Irish card game, see

Spoil Five Twenty-five is the Irish national card game, which also underlies the Canadian game of Forty-fives. Charles Cotton describes it in 1674 as "Five Fingers", a nickname applied to the Five of Trumps extracted from the fact that the Irish word ''cúig ...

. *The per-second frame rate of the

PAL Phase Alternating Line (PAL) is a colour encoding system for analogue television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields (25 ...

video standard. *The name of

Adele Adele Laurie Blue Adkins (, ; born 5 May 1988), professionally known by the mononym Adele, is an English singer and songwriter. After graduating in arts from the BRIT School in 2006, Adele signed a reco ...

's 2015 album '' 25,'' named for her age in that year. *The number of the French department

Doubs Doubs (, ; ; frp, Dubs) is a department in the Bourgogne-Franche-Comté region in Eastern France. Named after the river Doubs, it had a population of 543,974 in 2019.semiconductor A semiconductor is a material which has an electrical resistivity and conductivity, electrical conductivity value falling between that of a electrical conductor, conductor, such as copper, and an insulator (electricity), insulator, such as glas ...

s are specifically given in a

datasheet A datasheet, data sheet, or spec sheet is a document that summarizes the performance and other characteristics of a product, machine, component (e.g., an electronic component), material, subsystem (e.g., a power supply), or software in sufficie ...

. *The number of panels on the weekly

TV Asahi JOEX-DTV (channel 5), branded as (also known as EX and and stylized as TV asahi), is a television station that is owned and operated by the subsidiary of certified broadcasting holding company , itself controlled by The Asahi Shimbun Compan ...

quiz show ''

Panel Quiz Attack 25 is a game show airing once weekly on the Asahi Broadcasting Corporation network in Japan. The program first aired on April 6, 1975. It was announced on July 7, 2021, that the show will be ending its 46-year run on September 26, 202https://www.a ...

''.

Slang names

* Pony (British slang for £25)Evans, I.H., ''Brewer's Dictionary of Phrase and Fable'', 14th ed., Cassell, 1990,

References

{{Integers, zero Integers