(-4

Natural number

← iii 4 5 →
-1 0 1 2 3 iv 5 half dozen 7 8 ix → List of numbers — Integers ← 0 x 20 30 40 50 threescore lxx 80 90 →
Cardinal	four
Ordinal	4th (fourth)
Numeral organisation	fourth
Factorization	22
Divisors	1, two, four
Greek numeral	Δ´
Roman numeral	IV, iv
Greek prefix	tetra-
Latin prefix	quadri-/quadr-
Binary	100two
Ternary	11iii
Octal	4viii
Duodecimal	iv12
Hexadecimal	foursixteen
Arabic, Kurdish	٤
Persian, Sindhi	۴
Shahmukhi, Urdu	۴
Ge'ez	፬
Bengali, Assamese	৪
Chinese numeral	四，亖，肆
Devanagari	४
Telugu	౪
Malayalam	൪
Tamil	௪
Hebrew	ד
Khmer	៤
Thai	๔
Kannada	೪
Burmese	၄

4 (4) is a number, numeral and digit. It is the natural number following 3 and preceding 5. It is the smallest blended number, and is considered unlucky in many Eastward Asian cultures.

In mathematics

4 is the smallest blended number, its proper divisors beingness 1 and 2.^[i]

4 is the smallest squared prime number (p ²) and the but even number in this form. 4 is also the simply square one more than than a prime number.

A number is a multiple of 4 if its last two digits are a multiple of 4.^[2] For example, 1092 is a multiple of 4 because 92 = four × 23.

In improver, ii + 2 = two × ii = 2² = four. Standing the pattern in Knuth's up-arrow notation, 2 ↑↑ ii = 2 ↑↑↑ 2 = 4, and and so on, for any number of up arrows.^[3] (That is, 2 [n] ii = 4 for every positive integer due north, where a [n] b is the hyperoperation.)

A four-sided aeroplane effigy is a quadrilateral (quadrangle), sometimes also called a tetragon. Information technology can be further classified every bit a rectangle, ellipsoidal, square, kite, or rhombus.

A solid effigy with four faces also equally four vertices is a tetrahedron,^[4] and 4 is the smallest possible number of faces (too as vertices) of a polyhedron.^[5] The regular tetrahedron is the simplest Platonic solid.^[vi] A tetrahedron, which tin too be called a 3-simplex, has four triangular faces and 4 vertices. Information technology is the simply self-dual regular polyhedron.^[7]

Four-dimensional space is the highest-dimensional space featuring more than three convex regular figures:

• Ii-dimensional: infinitely many convex regular polygons.
• Three-dimensional: five convex regular polyhedra (the five Ideal solids).
• 4-dimensional: six convex regular polychora.
• Five-dimensional and every college-dimensional: three regular convex polytopes (regular simplexes, hypercubes, cantankerous-polytopes).

4-dimensional differential manifolds have some unique properties. There is only one differential structure on ${\displaystyle \mathbb {R} ^{n}}$ except when n = 4, in which instance there are uncountably many.

The smallest not-cyclic group has four elements; it is the Klein four-grouping.^[8] Four is likewise the order of the smallest not-little groups that are not unproblematic.

Four is the merely integer north for which the (non trivial) alternating grouping A_n is not simple.

Four is the maximum number of dimensions of a real associative division algebra (the quaternions), by a theorem of Ferdinand Georg Frobenius.

The four-color theorem states that a planar graph (or, equivalently, a flat map of two-dimensional regions such as countries) can be colored using four colors, so that side by side vertices (or regions) are e'er different colors.^[9] Three colors are not, in full general, sufficient to guarantee this.^[10] The largest planar complete graph has four vertices.^[11]

Lagrange'south four-square theorem states that every positive integer can be written as the sum of at most 4 foursquare numbers.^[12] Three are non always sufficient; vii for instance cannot be written as the sum of three squares.^[13]

Each natural number divisible past 4 is a deviation of squares of 2 natural numbers, i.e. 4ten = y ² − z ² .

Four is the highest degree general polynomial equation for which in that location is a solution in radicals.^[xiv]

Listing of bones calculations

Multiplication	ane	2	3	iv	5	6	vii	8	ix	ten		eleven	12	13	fourteen	fifteen	sixteen	17	18	19	20		21	22	23	24	25		50	100	grand
iv × ten	4	8	12	16	20	24	28	32	36	40		44	48	52	56	60	64	68	72	76	fourscore		84	88	92	96	100		200	400	4000

Sectionalization	i	2	three	4	5	six	7	8	nine	10		11	12	13	14	15	16
iv ÷ ten	four	2	1.3	i	0.eight	0.half-dozen	0.571428	0.5	0.four	0.4		0.36	0.3	0.307692	0.285714	0.2half-dozen	0.25
x ÷ 4	0.25	0.5	0.75	1	1.25	one.five	i.75	2	ii.25	2.5		ii.75	three	3.25	iii.5	3.75	four

Exponentiation	1	2	3	4	5	6	7	8	9	10		11	12	xiii
4 x	4	sixteen	64	256	1024	4096	16384	65536	262144	1048576		4194304	16777216	67108864
x 4	one	16	81	256	625	1296	2401	4096	6561	10000		14641	20736	28561

Development of the Arabic digit

Two mod handwritten fours

Brahmic numerals represented 1, ii and 3 with as many lines. 4 was simplified by joining its four lines into a cross that looks like the modernistic plus sign. The Shunga would add together a horizontal line on acme of the digit, and the Kshatrapa and Pallava evolved the digit to a signal where the speed of writing was a secondary business. The Arabs' iv withal had the early concept of the cross, but for the sake of efficiency, was made in one stroke by connecting the "western" cease to the "northern" cease; the "eastern" end was finished off with a bend. The Europeans dropped the finishing curve and gradually made the digit less cursive, ending upwardly with a digit very close to the original Brahmin cross.^[15]

While the shape of the character for the digit 4 has an ascender in almost mod typefaces, in typefaces with text figures the glyph usually has a descender, equally, for example, in .

On the seven-segment displays of pocket calculators and digital watches, as well as certain optical character recognition fonts, four is seen with an open height.^[16]

Tv stations that operate on channel 4 have occasionally fabricated use of some other variation of the "open up 4", with the open portion beingness on the side, rather than the top. This version resembles the Canadian Aboriginal syllabics letter ᔦ. The magnetic ink character recognition "CMC-vii" font as well uses this variety of "4".^[17]

In religion

Buddhism

• Iv Noble Truths – Dukkha, Samudaya, Nirodha, Magga^[18]
• Four sights – observations which affected Prince Siddhartha deeply and fabricated him realize the sufferings of all beings, and compelled him to begin his spiritual journeying—an old man, a sick human, a dead man, and an ascetic^[19]
• 4 Great Elements – earth, h2o, burn, and air current^[xx]
• Four Heavenly Kings^[21]
• Four Foundations of Mindfulness – contemplation of the trunk, contemplation of feelings, contemplation of mind, contemplation of mental objects^[18]
• 4 Right Exertions^[22]
• Four Bases of Power^[23]
• Iv jhānas^[24]
• Four arūpajhānas^[25]
• Iv Divine Abidings – loving-kindness, compassion, sympathetic joy, and self-possession^[26]
• Four stages of enlightenment – stream-enterer, once-returner, not-returner, and arahant^[27]
• Four main pilgrimage sites – Lumbini, Bodh Gaya, Sarnath, and Kusinara^[18]

Judeo-Christian symbolism

• The Tetragrammaton is the four-letter proper name of God.^[28]
• Ezekiel has a vision of four living creatures: a man, a king of beasts, an ox, and an eagle.^[29]
• The iv Matriarchs (foremothers) of Judaism are Sarah, Rebekah, Leah, and Rachel.^[30]
• The Four Species (lulav, hadass, aravah and etrog) are taken as one of the mitzvot on the Jewish holiday of Sukkot. (Judaism)^[31]
• The 4 Cups of Vino to drink on the Jewish holiday of Passover. (Judaism)^[32]
• The Four Questions to be asked on the Jewish holiday of Passover. (Judaism)^[32]
• The Four Sons to exist dealt with on the Jewish holiday of Passover. (Judaism)^[32]
• The Four Expressions of Redemption to be said on the Jewish holiday of Passover. (Judaism)^[33]
• The four Gospels: Matthew, Mark, Luke, and John. (Christianity)^[34]
• The Four Horsemen of the Apocalypse ride in the Book of Revelation. (Christianity)^[35]
• The Iv holy cities of Judaism: Jerusalem, Hebron, Safed, and Tiberius^[36]

Hinduism

• There are iv Vedas: Rigveda, Samaveda, Yajurveda and Atharvaveda.^[37]
• In Puruṣārtha, there are four aims of human life: Dharma, Artha, Kāma, Moksha.^[38]
• The four stages of life Brahmacharya (student life), Grihastha (household life), Vanaprastha (retired life) and Sannyasa (renunciation).^[39]
• The 4 primary castes or strata of society: Brahmana (priest/teacher), Kshatriya (warrior/politician), Vaishya (landowner/entrepreneur) and Shudra (servant/manual laborer).^[40]
• The swastika symbol is traditionally used in Hindu religions equally a sign of good luck and signifies good from all four directions.^[41]
• The god Brahma has four faces.^[42]
• There are iv yugas: Satya, Dvapara, Treta and Kali ^[43]

Islam

• Eid al-Adha lasts for four days, from the 10th to the 14th of Dhul Hijja.^[44]
• The four holy cities of Islam: Mecca, Medina, Jerusalem and Damascus.
• The four tombs in the Greenish Dome: Muhammad, Abu Bakr, Umar ibn Khattab and Isa ibn Maryam (Jesus).
• There are four Rashidun or Rightly Guided Caliphs: Abu Bakr, Umar ibn al-Khattab, Uthman ibn Affan and Ali ibn Abi Talib.^[45]
• The Four Arch Angels in Islam are: Jibraeel (Gabriel), Mikaeel (Michael), Izraeel (Azrael), and Israfil (Raphael)^[46]
• There are 4 months in which war is not permitted: Muharram, Rajab, Dhu al-Qi'dah and Dhu al-Hijjah.^[47]
• There are four Sunni schools of fiqh: Hanafi, Shafi`i, Maliki and Hanbali.
• There are 4 major Sunni Imams: Abū Ḥanīfa, Muhammad ibn Idris ash-Shafi`i, Malik ibn Anas and Ahmad ibn Hanbal.
• There are 4 books in Islam: Taurait, Zaboor, Injeel, Quran.^[48]
• Waiting for four months is ordained for those who accept an oath for abstention from their wives.^[49]
• The waiting period of the woman whose husband dies, is 4 months and 10 days.^[50]
• When Abraham said: "My Lord, show me how You give life to the expressionless," Allah said: "Why! Do you lot take no faith?" Abraham replied: "Yes, merely in order that my heart exist at rest." He said: "And so take four birds, and tame them to yourself, then put a part of them on every colina, and summon them; they will come up to you lot flying. [Al-Baqara 2:260]^[51]
• The respite of four months was granted to give time to the mushriks in Surah At-Tawba so that they should consider their position carefully and decide whether to make preparation for war or to emigrate from the country or to accept Islam.^[52]
• Those who accuse honorable women (of unchastity) but practise not produce four witnesses, flog them with fourscore lashes, and do not acknowledge their testimony ever after. They are indeed transgressors. [An-Noor 24:iv]^[53]

Taoism

• Iv Symbols of I Ching^[54]

Other

• In a more general sense, numerous mythological and cosmogonical systems consider 4 corners of the world as essentially corresponding to the four points of the compass.^[55]
• Four is the sacred number of the Zia, an ethnic tribe located in the U.Southward. state of New United mexican states.^[56]
• The Chinese, the Koreans, and the Japanese are superstitious most the number four considering information technology is a homonym for "decease" in their languages.^[57]
• In Slavic mythology, the god Svetovid has iv heads.^[58]

In politics

• Four Freedoms: four central freedoms that Franklin D. Roosevelt declared ought to be enjoyed by anybody in the globe: Freedom of Speech, Freedom of Religion, Freedom from Want, Freedom from Fear.^[59]
• Gang of Four: Pop name for four Chinese Communist Party leaders who rose to prominence during China's Cultural Revolution, merely were ousted in 1976 post-obit the decease of Chairman Mao Zedong. Amidst the four was Mao's widow, Jiang Qing. Since so, many other political factions headed past iv people have been called "Gangs of Iv".^[60]

In computing

• Four $.25 (half a byte) are sometimes called a nibble.^[61]

In science

• A tetramer is an oligomer formed out of 4 sub-units.^[62]

In astronomy

• Four terrestrial (or rocky) planets in the Solar System: Mercury, Venus, World, and Mars.^[63]
• Iv giant gas/ice planets in the Solar System: Jupiter, Saturn, Uranus, and Neptune.^[64]
• Four of Jupiter's moons (the Galilean moons) are readily visible from Globe with a hobby telescope.^[65]
• Messier object M4, a magnitude 7.five globular cluster in the constellation Scorpius.^[66]
• The Roman numeral Iv stands for subgiant in the Yerkes spectral classification scheme.^[67]

In biological science

• Four is the number of nucleobase types in Deoxyribonucleic acid and RNA – adenine, guanine, cytosine, thymine (uracil in RNA).^[68]
• Many chordates have 4 anxiety, legs or leglike appendages (tetrapods).
• The mammalian heart consists of four chambers.^[69]
• Many mammals (Carnivora, Ungulata) use four fingers for movement.
• All insects with wings except flies and some others have iv wings.^[70]
• Insects of the superorder Endopterygota, also known as Holometabola, such every bit butterflies, ants, bees, beetles, fleas, flies, moths, and wasps, undergo holometabolism—complete metamorphism in iv stages—from (ane) embryo (ovum, egg), to (ii) larva (such as chow, caterpillar), and then (iii) pupa (such as the chrysalis), and finally (4) the imago.^[71]
• In the common ABO claret group system, at that place are four blood types (A, B, O, AB).^[72]
• Humans have four canines and four wisdom teeth.^[73]
• The cow'due south breadbasket is divided in four digestive compartments: reticulum, rumen, omasum and abomasum.^[74]

In chemistry

• Valency of carbon (that is basis of life on the Earth) is four. Also because of its tetrahedral crystal bond structure, diamond (i of the natural allotropes of carbon) is the hardest known naturally occurring material. Information technology is likewise the valence of silicon, whose compounds form the majority of the mass of the Globe'due south crust.^[75]
• The atomic number of beryllium^[76]
• There are iv basic states of matter: solid, liquid, gas, and plasma.^[77]

In physics

• Special relativity and general relativity treat nature as iv-dimensional: 3D regular space and one-dimensional fourth dimension are treated together and called spacetime.^[78] Also, any event Eastward has a light cone composed of four zones of possible communication and cause and effect (outside the calorie-free cone is strictly incommunicado).
• There are iv primal forces (electromagnetism, gravitation, the weak nuclear forcefulness, and the strong nuclear force).^[79]
• In statistical mechanics, the 4 functions inequality is an inequality for iv functions on a finite distributive lattice.^[lxxx]

In logic and philosophy

• The symbolic meanings of the number four are linked to those of the cross and the square. "Almost from prehistoric times, the number four was employed to signify what was solid, what could be touched and felt. Its relationship to the cross (four points) fabricated it an outstanding symbol of wholeness and universality, a symbol which drew all to itself". Where lines of latitude and longitude intersect, they divide the earth into iv proportions. Throughout the world kings and chieftains have been called "lord of the four suns" or "lord of the four quarters of the globe",^[81] which is understood to refer to the extent of their powers both territorially and in terms of total command of their subjects' doings.
• The Square of Opposition, in both its Aristotelian version and its Boolean version, consists of iv forms: A ("All South is R"), I ("Some South is R"), E ("No S is R"), and O ("Some S is non R").
• In regard to whether two given propositions can accept the aforementioned truth value, there are 4 separate logical possibilities: the propositions are subalterns (peradventure both are true, and possibly both are fake); subcontraries (it is possible that both are true, but not that both are false); contraries (it is possible that both are false, but not that both are true); or contradictories (it is not possible that both are true, and it is not possible that both are false).
• Aristotle held that there are basically iv causes in nature: the fabric, the formal, the efficient,and the last.^[82]
• The Stoics held with four basic categories, all viewed as bodies (substantial and insubstantial): (one) substance in the sense of substrate, primary formless thing; (two) quality, matter's organisation to differentiate and individualize something, and coming down to a physical ingredient such every bit pneuma, breath; (3) somehow holding (or disposed), every bit in a posture, state, shape, size, action, and (4) somehow holding (or disposed) toward something, as in relative location, familial relation, so forth.
• Immanuel Kant expounded a table of judgments involving iv 3-mode alternatives, in regard to (1) Quantity, (2) Quality, (iii) Relation, (iv) Modality, and, based thereupon, a tabular array of four categories, named by the terms just listed, and each with iii subcategories.
• Arthur Schopenhauer's doctoral thesis was On the Fourfold Root of the Principle of Sufficient Reason.
• Franz Brentano held that any major philosophical period has 4 phases: (1) Creative and rapidly progressing with scientific interest and results; and then declining through the remaining phases, (ii) applied, (3) increasingly skeptical, and (iv) literary, mystical, and scientifically worthless—until philosophy is renewed through a new menstruation'south first phase. (See Brentano'due south essay "The 4 Phases of Philosophy and Its Current State" 1895, tr. by Mezei and Smith 1998.)
• C. Southward. Peirce, usually a trichotomist, discussed iv methods for overcoming troublesome uncertainties and achieving secure behavior: (ane) the method of tenacity (policy of sticking to initial belief), (2) the method of authority, (3) the method of congruity (post-obit a fashionable paradigm), and (4) the fallibilistic, self-correcting method of science (encounter "The Fixation of Conventionalities", 1877); and four barriers to inquiry, barriers refused by the fallibilist: (1) assertion of absolute certainty; (2) maintaining that something is absolutely unknowable; (three) maintaining that something is absolutely inexplicable because absolutely basic or ultimate; (4) belongings that perfect exactitude is possible, especially such as to quite preclude unusual and anomalous phenomena (come across "F.R.L." [First Rule of Logic], 1899).
• Paul Weiss built a system involving four modes of beingness: Actualities (substances in the sense of substantial, spatio-temporally finite beings), Ideality or Possibility (pure normative form), Existence (the dynamic field), and God (unity). (See Weiss's Modes of Being, 1958).
• Karl Popper outlined a tetradic schema to describe the growth of theories and, via generalization, also the emergence of new behaviors and living organisms: (1) problem, (2) tentative theory, (3) (attempted) error-elimination (especially by mode of critical word), and (iv) new problem(south). (See Popper's Objective Knowledge, 1972, revised 1979.)
• John Boyd (military strategist) made his key concept the decision cycle or OODA loop, consisting of four stages: (1) ascertainment (data intake through the senses), (2) orientation (analysis and synthesis of data), (iii) decision, and (four) activeness.^[83] Boyd held that his decision cycle has philosophical generality, though for strategists the point remains that, through swift decisions, one can disrupt an opponent's decision cycle.
• Richard McKeon outlined four classes (each with four subclasses) of modes of philosophical enquiry: (ane) Modes of Being (Being); (2) Modes of Idea (That which is); (3) Modes of Fact (Existence); (4) Modes of Simplicity (Experience)—and, corresponding to them, iv classes (each with 4 subclasses) of philosophical semantics: Principles, Methods, Interpretations, and Selections. (See McKeon's "Philosophic Semantics and Philosophic Enquiry" in Liberty and History and Other Essays, 1989.)
• Jonathan Lowe (E.J. Lowe) argues in The Four-Category Ontology, 2006, for four categories: kinds (substantial universals), attributes (relational universals and property-universals), objects (substantial particulars), and modes (relational particulars and property-particulars, also known equally "tropes"). (See Lowe'south "Recent Advances in Metaphysics," 2001, Eprint)
• Iv opposed camps of the morality and nature of evil: moral absolutism, amoralism, moral relativism, and moral universalism.

In engineering science

4 as a resin identification lawmaking, used in recycling

• The resin identification code used in recycling to identify low-density polyethylene.^[84]
• Most furniture has iv legs – tables, chairs, etc.
• The iv color procedure (CMYK) is used for printing.^[85]
• Wide use of rectangles (with four angles and four sides) because they accept constructive form and adequacy for close adjacency to each other (houses, rooms, tables, bricks, sheets of paper, screens, pic frames).
• In the Rich Text Format specification, linguistic communication code 4 is for the Chinese linguistic communication. Codes for regional variants of Chinese are congruent to 4 mod 256.
• Credit menu machines have four-twelve function keys.
• On most phones, the 4 cardinal is associated with the letters M, H, and I,^[86] but on the BlackBerry cellular phone, information technology is the primal for D and F.
• On many figurer keyboards, the "4" central may also be used to type the dollar sign ($) if the shift key is held downwardly.
• It is the number of bits in a nibble, equivalent to half a byte^[87]
• In internet slang, "4" can replace the discussion "for" (as "four" and "for" are pronounced similarly). For example, typing "4u" instead of "for y'all".
• In Leetspeak, "four" may be used to supersede the letter "A".
• The TCP/IP stack consists of four layers.^[88]

In transport

• Many internal combustion engines are called four-stroke engines considering they complete one thermodynamic cycle in four distinct steps: Intake, pinch, ability, and exhaust.
• Near vehicles, including motor vehicles, and peculiarly cars/automobiles and lite commercial vehicles have four road wheels.
• "Quattro", meaning 4 in the Italian linguistic communication, is used past Audi as a trademark to signal that all-wheel bulldoze (AWD) technologies are used on Audi-branded cars.^[89] The word "Quattro" was initially used by Audi in 1980 in its original 4WD coupé, the Audi Quattro. Audi also has a privately held subsidiary company chosen quattro GmbH.
• List of highways numbered 4

In sports

• In the Australian Football League, the tiptop level of Australian rules football, each team is immune 4 "interchanges" (substitute players), who tin be freely substituted at any time, subject to a limit on the total number of substitutions.
• In baseball:
  • There are four bases in the game: first base, 2nd base, third base, and abode plate; to score a run, an offensive player must complete, in the sequence shown, a excursion of those four bases.
  • When a batter receives four pitches that the umpire declares to be "assurance" in a single at-bat, a base on balls, informally known every bit a "walk", is awarded, with the batter sent to start base.
  • For scoring, number four is assigned to the second baseman.
  • Four is the most runs that can exist scored on any single at bat, whereby all three baserunners and the batter score (the most common being via a grand slam).
• In basketball, the number four is used to designate the power forrard position, often referred to every bit "the iv spot" or "the four".^[ninety]
• In cricket, a four is a specific blazon of scoring event, whereby the brawl crosses the purlieus after touching the footing at least in one case, scoring 4 runs. Taking four wickets in four consecutive balls is typically referred to as a double chapeau trick (two consecutive, overlapping hat tricks).
• In rowing, a four refers to a boat for four rowers, with or without coxswain. In rowing classification, 4− represents a coxless four and four+ represents a coxed four.
• In rugby league:
  • A effort is worth 4 points.
  • One of the 2 starting centres wears the jersey number iv. (An exception to this rule is the Super League, which uses static squad numbering.)
• In rugby union:
  • One of the ii starting locks wears the bailiwick of jersey number iv.
  • In the standard bonus points organisation, a point is awarded in the league standings to a team that scores at to the lowest degree 4 tries in a friction match, regardless of the match result.

In other fields

• The phrase "four-letter of the alphabet word" is used to draw many swear words in the English language.^[91]

• Iv is the simply number whose proper noun in English has the aforementioned number of messages every bit its value.
• Four ( 四 , formal writing: 肆 , pinyin sì) is considered an unlucky number in Chinese, Korean, Vietnamese and Japanese cultures mostly in Eastern Asia because it sounds like the word "death" ( 死 , pinyin sǐ). To avoid complaints from people with tetraphobia, many numbered product lines skip the "four": e.g. Nokia cell phones (there was no serial kickoff with a iv until the Nokia 4.two), Palm PDAs, etc. Some buildings skip flooring 4 or replace the number with the letter "F", particularly in heavily Asian areas. Run across tetraphobia and Numbers in Chinese civilisation.
• In Pythagorean numerology (a pseudocience) the number 4 represents security and stability.
• The number of characters in a canonical four-character idiom.
• In the NATO phonetic alphabet, the digit 4 is called "fower".^[92]
• In Star divination, Cancer is the 4th astrological sign of the Zodiac.^[93]

• In Tarot, The Emperor is the fourth trump or Major Arcana card.^[94]
• In Tetris, a game named for the Greek word for 4, every shape in the game is formed of 4 blocks each.^{[95] [96]}
• 4 represents the number of Justices on the Supreme Court of the United States necessary to grant a writ of certiorari (i.eastward., hold to hear a instance; it is ane less than the number necessary to return a majority decision) at the courtroom'due south electric current size.^[97]
• Number Iv is a grapheme in the volume series Lorien Legacies. ^[98]
• In the performing arts, the fourth wall is an imaginary bulwark which separates the audience from the performers, and is "broken" when performers communicate directly to the audition.^[99]

In music

• In written music, common time is constructed of four beats per measure and a quarter annotation receives 1 beat.^[100]
• In popular or modernistic music, the most common time signature is also founded on four beats, i.e., four/iv having four quarter note beats.
• The common major scale is built on 2 sets of iv notes (e.g., CDEF, GABC), where the commencement and last notes create an octave interval (a pair-of-four human relationship).
• The interval of a perfect fourth is a foundational element of many genres of music, represented in music theory as the tonic and subdominant relationship. Four is also embodied inside the circle of fifths (also known as circle of fourths), which reveals the interval of four in more than active harmonic contexts.
• The typical number of movements in a symphony.^[101]
• The number of completed, numbered symphonies past Johannes Brahms.^[102]
• The number of strings on a violin, a viola, a cello, double bass, a cuatro and a ukulele, and the number of string pairs on a mandolin.
• "Iv calling birds" is the souvenir on the fourth day of Christmas in the carol "The Twelve Days of Christmas".^[103]

Groups of four

• Large Iv (disambiguation)
• 4 bones operations of arithmetics: addition, subtraction, multiplication, sectionalisation.^[104]
• Greek classical elements (fire, air, water, globe).^[105]
• Four seasons: jump, summer, autumn, wintertime.
• The Four Seasons (disambiguation)
• A leap yr generally occurs every four years.^[106]
• Approximately iv weeks (4 times vii days) to a lunar month (synodic calendar month = 29.53 days). Thus the number 4 is universally an integral part of primitive sacred calendars.
• 4 weeks of Appearance (and four Advent candles on the Appearance wreath).
• Four cardinal directions: north, south, east, west.^[107]
• 4 Temperaments: sanguine, choleric, melancholic, phlegmatic.
• Iv Humors: claret, yellow bile, blackness bile, phlegm.^[108]
• Four Great Aboriginal Capitals of China.
• 4-corner method.
• Four Asian Tigers, referring to the economies of Hong Kong, Taiwan, Republic of korea, and Singapore
• Primal principles.
• Iv primal virtues: justice, prudence, temperance, fortitude.
• 4 suits of playing cards: hearts, diamonds, clubs, spades.^[109]
• Four nations of the United Kingdom: England, Wales, Scotland, Northern Ireland.
• Four provinces of Ireland: Munster, Ulster, Leinster, Connacht.
• Four estates: politics, administration, judiciary, journalism. Especially in the expression "Fourth Estate", which means journalism.
• Iv Corners is the only location in the United States where 4 states come together at a unmarried betoken: Colorado, Utah, New Mexico, and Arizona.
• 4 Evangelists – Matthew, Mark, Luke, and John
• 4 Doctors of Western Church – Saint Gregory the Great, Saint Ambrose, Saint Augustine, and Saint Jerome
• Four Doctors of Eastern Church building – Saint John Chrysostom, Saint Basil the Great, and Gregory of Nazianzus and Saint Athanasius
• Four Galilean moons of Jupiter – Io, Europa, Ganymede, and Callisto
• The Gang of Four was a Chinese communist political faction.
• The Fantastic Four: Mr. Fantastic, The Invisible Woman, The Homo Torch, The Affair.
• The Teenage Mutant Ninja Turtles: Leonardo, Michelangelo, Donatello, Raphael
• The Beatles were also known as the "Fab Iv": John Lennon, Ringo Starr, George Harrison, Paul McCartney.
• Gang of Four is a British mail-punk rock band formed in the late 1970s.
• Four rivers in the Garden of Eden (Genesis 2:10–14): Pishon (perhaps the Jaxartes or Syr Darya), Gihon (perhaps the Oxus or Amu Darya), Hiddekel (Tigris), and P'rat (Euphrates).
• In that location are also iv years in a single Olympiad (duration between the Olympic Games). Many major international sports competitions follow this cycle, among them the FIFA World Cup and its women'southward version, the FIBA World Championships for men and women, and the Rugby World Cup.
• There are four limbs on the human body.
• Four Houses of Hogwarts in the Harry Potter serial: Gryffindor, Hufflepuff, Ravenclaw, Slytherin.^[110]
• Four known continents of the world in the A Song of Ice and Burn down series: Westeros, Essos, Sothoryos, Ulthos.
• Each Grand Prix in Nintendo'due south Mario Kart series is divided into 4 cups and each cup is divided into four courses. The Mushroom Cup, Flower Cup, Star Cup, and Special Cup brand up the Nitro Grand Prix, while the Shell Cup, Assistant Cup, Leaf Cup, and the Lightning Cup make up the Retro One thousand Prix.

See also

• List of highways numbered 4

References

1. ^ Fiore, Gregory (1993-08-01). Basic mathematics for college students: concepts and applications. HarperCollins College. p. 162. ISBN978-0-06-042046-8. The smallest composite number is 4.
2. ^ Prep, Kaplan Test (2017-01-03). Sat Subject Test Mathematics Level i. Simon and Schuster. p. 289. ISBN978-1-5062-0922-7. An integer is divisible past 4 if the last two digits form a multiple of iv.
3. ^ Hodges, Andrew (2008-05-17). 1 to 9: The Inner Life of Numbers. W. W. Norton & Company. p. 249. ISBN978-0-393-06863-iv. 2 ↑↑ ... ↑↑ ii is always 4
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6. ^ Grossnickle, Foster Earl; Reckzeh, John (1968). Discovering Meanings in Uncomplicated Schoolhouse Mathematics. Holt, Rinehart and Winston. p. 337. ISBN9780030676451. ...face of the platonic solid. The simplest of these shapes is the tetrahedron...
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25. ^ Jayatilleke, G. North. (2013-10-16). Early Buddhist Theory of Knowledge. Routledge. ISBN978-1-134-54294-ix. ...u.s. of the four arupajhanas.
26. ^ Gorkom, Nina van. The Perfections Leading to Enlightenment. Рипол Классик. p. 171. ISBN978-v-88139-786-9. There are iv of them: loving-kindness, metta, compassion, karuna, sympathetic joy, mudita and equanimity, upekkha.
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29. ^ Stevenson, Kenneth; Glerup, Michael (2014-03-19). Ezekiel, Daniel. InterVarsity Press. pp. xlv. ISBN978-0-8308-9738-4. We take already mentioned the iv living creatures—the man, the lion, the ox and the eagle
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32. ^ ^{a b c} Dennis, Geoffrey W. (2007). The Encyclopedia of Jewish Myth, Magic and Mysticism. Llewellyn Worldwide. p. 188. ISBN978-0-7387-0905-5. The Passover Seder is peculiarly structured around fours: the Four Questions, the Four Sons, and four cups of wine.
33. ^ "Four Expressions of Redemption to be said on the Jewish vacation of Passover - Google Search". www.google.com. p. 46. Retrieved 2020-07-29 . In that location are 4 expressions of redemption in the Torah
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35. ^ Wagner, Richard; Helyer, Larry R. (2011-01-31). The Book of Revelation For Dummies. John Wiley & Sons. p. 308. ISBN978-1-118-05086-6. The 4 horsemen of the Apocalypse are one of the most familiar images of Revelation
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40. ^ Chwalkowski, Farrin (2016-12-14). Symbols in Arts, Religion and Culture: The Soul of Nature. Cambridge Scholars Publishing. p. 23. ISBN978-1-4438-5728-iv. The four primary castes or strata of social club:...
41. ^ Kulendiren, Pon (2012-10-eleven). Hinduism a Scientific Organized religion: & Some Temples in Sri Lanka. iUniverse. p. 32. ISBN978-1-4759-3675-9.
42. ^ Jansen, Eva Rudy (1993). The Book of Hindu Imagery: Gods, Manifestations and Their Meaning. Binkey Kok Publications. p. 87. ISBN978-xc-74597-07-4. Brahma has four faces,...
43. ^ "Definition of yuga | Dictionary.com". www.dictionary.com . Retrieved 2020-07-28 .
44. ^ Çakmak, Cenap (2017-05-eighteen). Islam: A Worldwide Encyclopedia [four volumes]. ABC-CLIO. p. 397. ISBN978-1-61069-217-5. ...Eid al-Adha (Feast of Sacrifice) lasts iv days ...
45. ^ Leonard, Timothy; Willis, Peter (2008-06-eleven). Pedagogies of the Imagination: Mythopoetic Curriculum in Educational Practice. Springer Science & Business Media. p. 144. ISBN978-i-4020-8350-one. ... 4 Rightly Guided Caliphs, Abu-Bakr, Umar ibn al-Khattab, Uthman ibn Affan and Ali ibn Abi Talib,...
46. ^ Chwalkowski, Farrin (2016-12-14). Symbols in Arts, Organized religion and Civilisation: The Soul of Nature. Cambridge Scholars Publishing. p. 23. ISBN978-1-4438-5728-4. Co-ordinate to Islam, the Four Arch Angels are: Jibraeel (Gabriel), Mikaeel (Michael), Izraeel (Azrael), and Israfil (Raphael).
47. ^ Ph.D, Assad Nimer Busool (2010-12-28). The Wise Qur'an: These are the Verses of the Wise Book: These are the verses of the Wise Book. Xlibris Corporation. p. 50. ISBN978-1-4535-2526-5. The sacred months are four, Rajab, Dhu al-Qi'dah, Dhu al-Hijjah, and al-Muharram. During those four sacred months in that location were no war...
48. ^ Shabazz, Hassan (2020-01-06). Al Islaam, and the Transformation of Society. Lulu.com. p. fifteen. ISBN978-one-7948-3337-1. In that location are four books in Islam: Torah, Zaboor, Injeel and Holy Qur'an...
49. ^ BUKHARI, MUOHAMMAD BEN ISMAIL AL (2007-01-01). THE CORRECT TRADITIONS OF AL'BUKHARI 1-4 VOL 3: صحيح البخاري i/four [عربي/انكليزي] ج3. Dar Al Kotob Al Ilmiyah دار الكتب العلمية. p. 840. For those who accept an adjuration for abstention from their wives, pending for four months is ordained;
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53. ^ Barazangi, Nimat Hafez (2016-03-09). Woman'southward Identity and Rethinking the Hadith. Routledge. p. 138. ISBN978-one-134-77065-6. And those who launch a charge against chaste women and practise not produce four witnesses...
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63. ^ Yaqoob, Tahir (2011). Exoplanets and Conflicting Solar Systems. New Earth Labs. p. 12. ISBN978-0-9741689-2-0. The four inner planets (known as terrestrial, or rocky planets
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84. ^ Howard, Brian Clark; Abdelrahman, Amina Lake; Constitute, Good Housekeeping (2020-02-26). "Y'all Might Be Recycling Incorrect — Hither's Everything You Need to Know About Recycling Symbols". Skilful Housekeeping . Retrieved 2020-07-28 . Plastic Recycling Symbol #iv: LDPE
85. ^ Conover, Charles (2011-11-08). Designing for Print. John Wiley & Sons. p. 62. ISBN978-ane-118-13088-nine. CMYK is the standard iv-color model used for all full-color print jobs that volition exist output on an starting time press press
86. ^ Vermaat, Misty East.; Sebok, Susan L.; Freund, Steven M.; Campbell, Jennifer T.; Frydenberg, Marker (2015-01-01). Discovering Computers, Essentials. Cengage Learning. p. 123. ISBN978-one-305-53402-5. ...the iv key (labeled with the letters g,h and i)...
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88. ^ Braden, R. "Requirements for Net Hosts - Communication Layers". tools.ietf.org. pp. ix–ten. Retrieved 2020-07-28 .
89. ^ Magazines, Hearst (1982). Popular Mechanics. Hearst Magazines.
90. ^ Schaller, Bob; Harnish, Dave (2009-09-18). The Everything Kids' Basketball Book: The best greats, legendary teams, today's superstars - and tips on playing like a pro. Simon and Schuster. ISBN978-1-4405-0177-7. Power forward Referred to as the number 4 spot
91. ^ "Definition of FOUR-Letter Word". www.merriam-webster.com . Retrieved 2020-07-28 .
92. ^ Wells, J. C. (2014-09-25). Sounds Interesting: Observations on English and General Phonetics. Cambridge University Press. p. 33. ISBN978-ane-316-12385-0. But one confused re-spelling is fower for '4'.
93. ^ Guttman, Ariel; Guttman, Gail; Johnson, Kenneth (1993). Mythic Astrology: Archetypal Powers in the Horoscope. Llewellyn Worldwide. p. 263. ISBN978-0-87542-248-0. Sign: Cancer, the fourth Zodiacal Sign
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95. ^ Weller, David; Lobao, Alexandre Santos; Hatton, Ellen (2004-09-20). Commencement .Internet Game Programming in VB .NET. Apress. p. 383. ISBN978-1-4302-0724-v. ...tetraminos (the shapes used in Tetris) are all simply a drove of four blocks
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97. ^ Bardes, Barbara; Shelley, Mack; Schmidt, Steffen (2008-12-16). American Government and Politics Today: The Essentials 2009 - 2010 Edition. Cengage Learning. p. 453. ISBN978-0-495-57170-4. The courtroom will not issue a writ unless at to the lowest degree four justices approve of it. This is called the rule of iv.
98. ^ "Movie Projector: 'I Am Number Four' to be No. 1 at holiday weekend box function [Updated]". LA Times Blogs - Company Town. 2011-02-17. Retrieved 2020-07-28 .
99. ^ "fourth wall". dictionary.cambridge.org . Retrieved 2021-eleven-29 .
100. ^ Roberts, Gareth Eastward. (2016-02-15). From Music to Mathematics: Exploring the Connections. JHU Printing. p. iii. ISBN978-1-4214-1918-3. ... called common time and denoted by C, which has iv beats per mensurate
101. ^ Bonds, Marker Evan (2009-01-10). Music as Thought: Listening to the Symphony in the Age of Beethoven. Princeton University Press. p. 1. ISBN978-1-4008-2739-8. The number, character and sequence of movements in the symphony, moreover, did not stabilize until the 1770s when the familiar format of iv movements...
102. ^ Frisch, Walter (2003). Brahms: The Four Symphonies. Yale Academy Printing. ISBN978-0-300-09965-2.
103. ^ Brech, Lewis (2010). Storybook Advent Carols Collection Songbook. Couples Company, Inc. p. 26. ISBN978-i-4524-7763-3.
104. ^ Wright, Robert J.; Ellemor-Collins, David; Tabor, Pamela D. (2011-xi-04). Developing Number Knowledge: Assessment,Teaching and Intervention with 7-11 twelvemonth olds. SAGE. ISBN978-one-4462-5368-seven.
105. ^ Macauley, David (2010-09-29). Elemental Philosophy: Earth, Air, Fire, and Water every bit Environmental Ideas. SUNY Printing. ISBN978-1-4384-3246-5.
106. ^ Brooks, Edward (1876). Normal College Arithmetic Designed for Advanced Classes in Mutual Schools, Normal Schools, and High Schools, Academics, Etc. Sower. p. 227. Every year that is divisible by four, except the Centennial years, and every Centennial year divisible by 400, is a leap year...
107. ^ Touche, Fred; Price, Anne (2005). Wilderness Navigation Handbook. Touche Publishing. p. 48. ISBN978-0-9732527-0-5. Each of the familiar fundamental directions is equivalent to a item true bearing:north (0°), east (90°), south (180°),and west (270°)
108. ^ Roeckelein, J. East. (2006-01-xix). Elsevier'southward Dictionary of Psychological Theories. Elsevier. p. 235. ISBN978-0-08-046064-2. ...four substances or humors: claret, yellowish bile, blackness bile and phlegm
109. ^ Medley, H. Anthony (1997). Bridge. Penguin. p. six. ISBN978-0-02-861735-0. The four playing card suits, as you lot probably already know, are spades, hearts, diamonds, and clubs
110. ^ Baker, Felicity (2017). Houses of Hogwarts: Cinematic Guide. Scholastic Incorporated. ISBN978-1-338-12861-one. ...the four houses of Hogwarts School of Witchcraft and Wizardry: Gryffindor, Ravenclaw, Hufflepuff, and Slytherin

• Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group. (1987): 55–58

External links

Look up four in Wiktionary, the complimentary dictionary.

Wikimedia Commons has media related to four (number).

• Marijn.Org on Why is everything four?
• A few thoughts on the number four, by Penelope Merritt at samuel-beckett.internet
• The Number four
• The Positive Integer 4
• Prime number curiosities: 4

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Source: https://en.wikipedia.org/wiki/4

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