3: Difference between revisions

	3
	Template:Numbers (digits)
Cardinal	3 ; three
Ordinal	3rd ; third
Numeral system	ternary
Factorization	prime
Divisors	1, 3
Roman numeral	III
Roman numeral (Unicode)	Ⅲ, ⅲ
Arabic	٣
Ge'ez	፫
Bengali	৩
Chinese numeral	三，弎，叁
Devanāgarī	३
Hebrew	ג (Gimel)
Khmer	៣
Thai	๓
prefixes	tri- (from Greek) tre-/ter- (from Latin)
Binary	11
Octal	3
Duodecimal	3
Hexadecimal	3

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3 (three) is a number, numeral, and glyph. It is the natural number following 2 and preceding 4.

In mathematics

Three is the first odd prime number, and the second smallest prime. It is both the first Fermat prime (2^2º + 1) and the first Mersenne prime (2² - 1), as well as the first lucky prime. However, it's the second Sophie Germain prime, the second Mersenne prime exponent, the second factorial prime (2! + 1), the second Lucas prime, the second Stern prime.

Three is the first unique prime due to the properties of its reciprocal.

Three is the third Heegner number.

Three is the second triangular number and it is the only prime triangular number. Three is the only prime which is one less than a perfect square. Any other number which is n² - 1 for some integer n is not prime, since it is (n - 1)(n + 1). This is true for 3 as well, but in its case one of the factors is 1.

Three non-collinear points determine a plane and a circle.

Three is the fourth Fibonacci number and the third that is unique. In the Perrin sequence, however, 3 is both the zeroth and third Perrin numbers.

Three is the fourth open meandric number.

Vulgar fractions with 3 in the denominator have a single digit repeating sequences in their decimal expansions, (.000..., .333..., .666...)

A natural number is divisible by three if the sum of its digits in base 10 is divisible by 3. For example, the number 21 is divisible by three (3 times 7) and the sum of its digits is 2 + 1 = 3. Because of this, the reverse of any number that is divisible by three (or indeed, any permutation of its digits) is also divisible by three. For instance, 1368 and its reverse 8631 are both divisible by three (and so are 1386, 3168, 3186, 3618, etc..). See also Divisibility rule.

A triangle is the most durable shape possible, the only "perfect" figure which if all endpoints have hinges will never change its shape unless the sides themselves are bent.

3 is the only integer between e and π.

Three of the five regular polyhedra have triangular faces -- the tetrahedron, the octahedron, and the icosahedron. Also, three of the five regular polyhedra have vertices where three faces meet -- the tetrahedron, the hexahedron (cube), and the dodecahedron. Furthermore, only three different types of polygons comprise the faces of the five regular polyhedra -- the triangle, the quadrilateral, and the pentagon.

There are only three distinct 4×4 panmagic squares.

Only three tetrahedral numbers are also perfect squares.

In numeral systems

It is frequently noted by historians of numbers that early counting systems often relied on the three-patterned concept of "One- Two- Many" to describe counting limits. In other words, in their own language equivalent way, early peoples had a word to describe the quantities of one and two, but any quantity beyond this point was simply denoted as "Many". As an extension to this insight, it can also be noted that early counting systems appear to have had limits at the numerals 2, 3, and 4. References to counting limits beyond these three indices do not appear to prevail as consistently in the historical record.

Base	Numeral system
2	binary	11
3	ternary	10
over 3 (decimal, hexadecimal)		3

List of basic calculations

Multiplication	1	2	3	4	5	6	7	8	9	10		11	12	13	14	15	16	17	18	19	20		21	22	23	24	25		50	100	1000
$3\times x$	3	6	9	12	15	18	21	24	27	30		33	36	39	42	45	48	51	54	57	60		63	66	69	72	75		150	300	3000

Division	1	2	3	4	5	6	7	8	9	10		11	12	13	14	15
$3\div x$	3	1.5	1	0.75	0.6	0.5	$0.{\overline {4}}2857{\overline {1}}$	0.375	$0.{\overline {3}}$	0.3		$0.{\overline {2}}{\overline {7}}$	0.25	$0.{\overline {2}}3076{\overline {9}}$	$0.2{\overline {1}}4285{\overline {7}}$	0.2
$x\div 3$	$0.{\overline {3}}$	$0.{\overline {6}}$	1	$1.{\overline {3}}$	$1.{\overline {6}}$	2	$2.{\overline {3}}$	$2.{\overline {6}}$	3	$3.{\overline {3}}$		$3.{\overline {6}}$	4	$4.{\overline {3}}$	$4.{\overline {6}}$	5

Exponentiation	1	2	3	4	5	6	7	8	9	10		11	12	13
$3^{x}\,$	3	9	27	81	243	729	2187	6561	19683	59049		177147	531441	1594323
$x^{3}\,$	1	8	27	64	125	216	343	512	729	1000		1331	1728	2197

Evolution of the glyph

Three is often the largest number written with as many lines as the number represents. The Romans tired of writing 4 as IIII, but to this day 3 is written as three lines in Roman and Chinese numerals. This was the way the Brahmin Indians wrote it, and the Gupta made the three lines more curved. The Nagari started rotating the lines clockwise and ending each line with a slight downward stroke on the right. Eventually they made these strokes connect with the lines below, and evolved it to a character that looks very much like a modern 3 with an extra stroke at the bottom. It was the Western Ghubar Arabs who finally eliminated the extra stroke and created our modern 3. (The "extra" stroke, however, was very important to the Eastern Arabs, and they made it much larger, while rotating the strokes above to lie along a horizontal axis, and to this day Eastern Arabs write a 3 that looks like a mirrored 7 with ridges on its top line): ٣^[1]

While the shape of the 3 character has an ascender in most modern typefaces, in typefaces with text figures the character usually has a descender, as, for example, in . In some French text-figure typefaces, though, it has an ascender instead of a descender.

A common variant of the digit 3 has a flat top, similar to the character Ʒ (ezh), sometimes used to prevent people from falsifying a 3 into an 8.

In science

*3-patterned general formula of the Scientific Method''*
1. The observation of the phenomena and the recording of facts.
2. The formulation of physical laws from the generalization of the phenomena.
3. The development of a theory that is used to predict new phenomena.

Anatomy

A human ear has three semicircular canals.
A human middle ear has three ossicles.

Anthropology

3 distinct species of the genus Homo:

Homo habilis "capable man"
Homo erectus "upright man"
Homo sapiens "wise man"

3 distinct species of the genus Paranthropus:

Paranthropus robustus
Paranthropus boisei
Paranthropus aethiopicus

3 Proconsul species:

Proconsul africanus
Proconsul major
Proconsul nyanzae

3 Pan troglodyte sub-species:

Pan Troglodytes Schweinfurthii- (Eastern Common Chimpanzee)
Pan Troglodytes Troglodytes- (Central Common Chimp)
Pan Troglodytes Verus- (Western Common Chimp)

3 types of primates:

Prosimians
Monkeys (old & new world)
Apes (lesser & greater apes, as well as humans)

3 social group types of the Great Apes:

Orangutans (Solitary - little amount of both sexes)
Gorillas (Harems - great amount of one sex)
Common Chimps (Live in territories defended by related males - great amount of both sexes)

Three traditional families of hominoid:

Hylobatidae- include the so-called lesser apes of Asia, the gibbons and siamangs.
Hominidae- include living humans and typically fossil apes that possess a suite of characteristics such as bipedalism, reduced canine size, and increasing brain size such as the australopithecines.
Pongidae- include the remaining African great apes including gorillas, chimpanzees, and the Asian orangutan.

Present day humans have been referred to as the 3rd chimpanzee.

Astronomy

There are three types of galaxies:

ellipticals,
spirals and
irregulars.

Globular Cluster M3 (also known as Messier Object 3 or NGC 5272) is a globular cluster in the Canes Venatici constellation.
The Roman numeral III stands for giant star in the Yerkes spectral classification scheme.
The Roman numeral III (usually) stands for the third-discovered satellite of a planet or minor planet (e.g. Pluto III)
In the constellation Orion, his belt is made up of 3 stars in a row.
Earth is the third planet in its local Solar System.

Biology (specific and general)

RNA has a triplet codon system.
DNA has a triplet codon system.
Proteins can have a single, double, or tertiary structure, with a composite of these called the quaternary.
Human chromosomes can present trisomy.
3 basic life domains: Archaea- Bacteria- and Eucaryota
3 phyla of Archaebacteria that are found mainly in extreme habitats where little

else can survive: Methanogens~ Halophiles~ Thermoacidophiles.

3 mammalian Germ layers: Endoderm- Mesoderm- Ectoderm
3 principal stages of glucose respiration: Glycolysis~ Krebs cycle~ Electron transport chain.

Chemistry

Three is the atomic number of lithium (Lithium is also the 33rd most abundant element on Earth).
Atoms consist of three constituents: protons, neutrons, and electrons.
3 types of molecular bond: Covalent~ Ionic~ Polar Covalent (Dative or Coordinate)
3 isomerism types: Structural (Ethyl alcohol) ~ Geometric (Maleic acid) ~ Optical (L-Lactic acid)
3 hydrocarbon chain types: Straight (Propane)~ Branched (Isobutane)~ Circular (Cyclopropane)
3 basic chemical reaction substances: Acids~ Bases~ Salts

Computer Science

Isaac Asimov's Three Laws of Robotics, which state:

A robot may not injure a human being or, through inaction, allow a human being to come to harm.
A robot must obey orders given to it by human beings, except where such orders would conflict with the First Law.
A robot must protect its own existence as long as such protection does not conflict with the First or Second Law.

Geology

Three basic planes: Above- Surfaced- Beneath
Three basic Earth divisions: Core- Mantle- Crust.
Three basic rock formations: Igneous- Metamorphic- Sedimentary.
In tectonic plate theory, the pacific plate's site can be said to be due to the "fusion" (engulfing) of 3 other plates: Izanagi plate~ Phoenix plate~ Kula plate.
3 types of earthquake waves: P (Primary) waves~ S (Secondary) waves~ L/R (Love & Rayleigh) waves.
3 types of volcanoes: Cinder cones~ Shield volcano~ Composite volcano.

History

Christian Jürgensen Thomsen proposed the three-age system to divide prehistory in the Stone, Bronze and Iron Ages.
3rd Reich of Germany: Adolf Hitler's Empire
3rd Rome: Old name for Russia
3rd Estate: French Revolution
3rd Way: Mussolini's social movement
3rd Wave: journalistic name given to Newt Gingrich's social movement (U.S.)
Third Communist International was founded in 1919 by Vladimir Ilyich Lenin (He died after a 3rd stroke).
Three most important events that led up to, and caused the American Revolution: Boston Massacre- Boston Tea Party~ Stamp Act.

Physics

There are three generations of fundamental leptons (electron, muon, tauon and their neutrinos) and three groups of flavours of quarks (up-down, charmed-strange, top-bottom).
A neutron consists of three quarks: two down quarks and one up quark.
We perceive our universe to have three spatial dimensions.

White light is composed of the mixture of the three additive primary hues: red, green, and blue.

Three is the minimum and maximum, a singular optimum, just sufficient to geometrically realize a topologically three-shell-substructured toroidal superstring with three different spins (no vacuum!) and enable its specific spin functionality (three different spin functionalities with three different spin states each). The main aspect of this functionality is quintessence in the state of supersymmetry, breaking of supersymmetry (weak interaction, change of flavor) and breaking of color supersymmetry of quarks with angular spins -1 0 +1 (green, red, blue).

Three is the smallest number that, in a physical realization, on breaking of symmetry allows the emergence of two additional functionalities different from the one of a central state. These either can be symmetric as in -3 (±0) +3 (electron, two supersymmetric superstrings (left/right-handed, no matter particles, dark), and the positron) or asymmetric as in -1 (-0) +2 (quarks) or -2 (+0) +1 (anti quarks). This means, breaking of a symmetry also can result in one of two different asymmetric states. In this case supersymmetry globally is conserved on the average by the properties of three quarks (enforced quark confinement). Multiplication of these angular spins by 1/3 gives the three particle charges, negative or positive are defined by the direction of angular spin.

Changes of spin, appearing as changes of flavor, only can be by three multiples of a fundamental angular quantum of spin causing an 1/3 elementary charge e. The down quark only can change its spin from -1 to +2, the up-quark. A supersymmetric superstring can break supersymmetry from -0 to -3 (electron) or from +0 to +3 (positron). The electron anti-neutrino (+3) and electron neutrino (-3)represent three quanta of fermionic spin within the spacetime metric (no superstrings/particles), conserving supersymmetry globally.

Nature defines the state of supersymmetry as ±0 (left- and right-handed). This allows additional variations with respect to the breaking of supersymmetry involving the number three. The whole spectrum of possibilities based on the number three thus is duplicated for matter and antimatter.

Three is realized as 0 1 2 in the number of exponents defining the basic kinds of spin. These are ½*2^0 ħ (fermionic), ½*2^1 ħ (bosonic), ½*2^2 ħ (gravitational). The bosonic state is the symmetric state.

Three non-gravitational forces actively are generated by three different superstring spin functionalities, while gravity is a passive reaction of spacetime due to the presence of superstrings with broken supersymmetry. It on principle is different.

Three represents an optimum of economy in a physical geometrical realization and a maximum of functionality at the same time. This limits the otherwise nearly infinite number of degrees of freedom by a defined geometry with a specific functionality to exactly the ones needed to generate the fundamental basis for the expression of the 'Everything'.

The number three is shown to be represented by different possible spin states in the regime from -3 to +3, that is by negative and positive integer numbers, including a -0 and +0, in contrast to mathematics where 0 is an integer number without sign. Due to geometrically defined quanta of spin the superstring shows a physical realization of integer numbers between -3 and +3. This answers Roger Penrose's question of the physical meaning of integer numbers (Road to Reality, p. 65) and their relevance in the physical world.

Three different states of string tension exist. The whole geometry and functionality is the same with exception of the orthogonal magnetic flux component causing gravo-magnetic mass. Thus three generations of particles can exist solely according to energetic conditions. The basic relevance of the number three for the superstring in no way is touched.

Physiology

3 distinct Cytoskeleton components: Microtubules~ Intermediate Filament~ Actin Filaments
3 primary cellular energy molecules: AMP~ ADP~ ATP
3 main fatty acid categories: Saturated~ Monounsaturated~ Polyunsaturated
3 substances metabolized for energy needs: Carbohydrates~ Fats~ Proteins
Triglycerides are the main storage forms of fatty acids.

Plants and Animals

Triceratops: Cretaceous period dinosaur with three horns on its head.
Shamrock: refers to one of several trifoliate (three-leaved) plants of the Leguminosae family which includes the clover.
3-bodied general description of insects: Head~ Thorax~ Abdomen.
Trilobite: hard-bodied invertebrate marine arthropod of the Paleozoic era with three lobes.
Monocotyledon: A monocot's flower is often trimerous, with the flower parts in threes or in multiples of three (typically three, six, or nine petals.)

Psychology

In his later work, Freud proposed that the psyche was divided into three parts: Ego, super-ego, and id. Freud discussed this structural model of the mind in the 1920 essay Beyond the Pleasure Principle, and fully elaborated it in The Ego and The Id (1923), where he developed it as an alternative to his previous topographic schema (conscious, unconscious, preconscious).

In religion and mythology

Georges Dumezil developed the idea of a Tripartite Ideology (Trifunctional Hypothesis) with respect to the Indo-European peoples consisting of three class divisions: Priestly~ Warrior~ Farmers/Craftsmen.
3 Indian Gods: Brahma, Vishnu, Maheshwara (Shiva)
3 Greek gods: Zeus~ Poseidon~ Hades (Air~ Water~ Earth)
3 Roman gods: Jupiter~ Neptune~ Pluto (Air~ Water~ Earth)
3 sons of Zeus & Europa: Minos~ Rhadamanthus~ Sarpedon
3 forms of Odin in Eddic Mythology: Har~ Jafnhar~ Thridi
3 mysterious figures amongst Norse gods: Hoenir~ Lodurr~ Mimir
Ancient Egypt Theban Triad: Amun~ Mut~ and their son Khans
3 ancient Egypt central religious figures: Horus~ Isis~ Osiris
3 items of manufacturer commonly attributed to Vulcan, God of fire and volcanoes: Art~ Arms~ Armor for gods and heroes.
The Maya believed 3 stars in the Orion Constellation (Alnitak~ Saiph~ Rigel) were arranged by the gods as a triangular hearth, enclosing the smoke of the fire creation - the nebula.
3 Greek Fates (Moirai, Moirés): Clotho~ Lachesis~ Atropos (sometimes referred to as the 3 spinners).
3 Roman Fates: Decima~ Nona (goddesses of birth)~ Morta (goddess of death)
3 Roman Graces- (in Greek mythology called the Charities and according to the Spartans, Cleta was the third): Aglaia~ Euphrosyne~ Thalia.
3 parts to a Chimera: Head of a lion~ Body of a goat~ Tail of a snake
3 monstrous offspring by Loki and Angroboda: Fenrir~ Hel~ Jormungund
3 hags possessing immense power in Norse Myth: Urdr~ Verdandi~ Skuld
3 Norns of Norse Mythology who sat beneath the World Tree Yggdrasil
3-faced goddess in Greek Mythology: Hecate
3 Gorgons-(snake-haired sisters in Greek mythology): Stheno, Euryale, Medusa are sometimes depicted as having wings of gold, brazen claws, and the tusks of boars. Medusa is the only one of the gorgons that is mortal.
3 different beings made up the different qualities of death according to ancient Greek belief: Thantos (male)~ Ker (female)~ Gorgo (female).
3 Roman Furies (female personifications of vengeance) that were called the Erinyes (the Angry Ones) or Eumenides by the Ancient Greeks (Orestes called them the Solemn Ones, or the Kindly Ones): Alecto ("unceasing")~ Megaera ("grudging")~ Tisiphone ("avenging murder").
3-headed dog that guarded the gate to Hades in Greek Mythology: Cerberus
3 ancient Greek Harpies: Aello, Ocypete, and Celaeno.

In Buddhism

The Triple Gem - Buddha, Dhamma (Buddha's teaching) and Sangha (the preachers of Dhamma)
The Triple Bodhi (ways to understand the end of birth)- Budhu, Pasebudhu, Mahaarahath

Abrahamic religions

The Shield of the Trinity is a diagram of the Christian doctrine of the Trinity

There are three main Abrahamic religions: Judaism, Christianity and Islam.
Noah's three sons:Shem, Ham and Japheth (Sons of Noah)
The Holy Trinity in Christian doctrine (or trinity in general), is God both as a single being and three persons: the Father, the Son and the Holy Spirit. This is also known as Tripartite division or the Godhead.
Jesus spread Christianity for 3 years.
Jesus rose from the dead on the third day after his death.
Jesus predicted that Peter would deny him three times.
The Wise Men who visited Jesus after His birth left Him three gifts.
In Muslim devotional rites, certain formulas are repeated three times, and others thirty-three times
A devout Muslim tries to make a pilgrimage to all three holy cities in Islam: Mecca, Medina, and Jerusalem
King Solomon states in Ecclesiastes 4:12: "A three-ply cord is not easily severed." Examples of this concept of three-ness in Judaism are:
- The three Patriarchs: Abraham, Isaac, and Jacob
- The three pilgrim festivals (Sheloshet HaRegalim): Passover, Shavuot, and Sukkot
- The three leaders of the Jewish nation during their 40 years of wandering in the desert: Moses, Aaron, and Miriam
- The Tanakh is comprised of 3 sections: Torah, Nevi'im, and Ketuvim
- There are 3 daily prayer services: Shacharit, Mincha, and Maariv
- There are three divisions of Jews: Kohen, Levi, and Israel
- Shimon Hatzaddik taught: "On three things the world stands: On Torah, on prayer, and on acts of kindness" (Pirkei Avoth 1:2). Rabban Shimon ben Gamliel taught: "The world continues to exist because of three things: justice, truth, and peace" (ibid. 1:18)
The three Theological virtues referred to 1 Corinthians 13.
In Roman Catholicism, three groups of martyrs, collectively known as Faith, Hope, and Charity (named after the Theological Virtues).
Heaven, Hell and Purgatory (or Limbo).

Other religions

The Wiccan Rule of Three.
The Triple Goddess: Maiden, Mother, Crone; the three fates.
In Taoism, the Three Pure Ones.
The three Gunas underlie action, in the Vedic system of knowledge. There is also the concept of Trimurti in Hindu tradition. The Buddha has three bodies. The three Vedas are called trayi i.e triad. Lord Shiva is Trinetra-Three-eyed. The confluence of the Ganga, Yamuna and hidden Sarasvati is the famous Triveni-confluence of three rivers. Buddhism's three refuges are Trisharana- Buddhan sharanam gacchami, Dhammam sharanam gacchami, Sangham sharanam gacchami.
In Greek mythology, the Three Graces or Charites. Also the number of heads of Cerberus, the monstrous dog that guards the gate to Hades
Various Triple deities.

In esoteric tradition

The Theosophical Society has three conditions of membership.
Gurdjieff's Three Centers and the Law of Three.
Aleister Crowley's model of the three schools of magick (Black, White and Yellow) from his Magick Without Tears.
Feri Tradition teaches of the existence of three souls in each individual person.

In fictional religion

In The Legend of Zelda video game series, a divine relic called the Triforce is represented by 3 Golden triangles. The Triforce was fashioned by a trio of goddesses who represented power, wisdom, and courage, and the sections of the Triforce each represent one of the three.

In philosophy

Plato split the soul into three parts: the appetitive, the spirited, and the rational
Hegel's dialectic of Thesis + Antithesis = Synthesis creates three-ness from two-ness.
The three Doshas (weaknesses) and their antidotes are the basis of Ayurvedic medicine in India.
Charles Sanders Peirce was a trichotomist and stipulated, among other things, a triadic relation of interpretant, representamen, and object to explain the phenomenon of semeiosis.

**3-patterned Philosophical Distinctions**
St. Augustine's Philosophy:	Memory~ Understanding~ Will
Aquinas's 3 transcendentals of being:	Unity~ Truth~ Goodness
Aquinas's 3 requisites for the beautiful:	Wholeness or perfection~ Harmony or due proportion~ Radiance
Aquinas's 3 logical faculties (based in Aristotle)	Conception~ Judgment~ Reasoning
Aquinas's 3 causal principles (based in Aristotle)	Agent~ Patient~ Act
Comte's Philosophy:	Great Being~ Great Medium~ Great Fetish
Hegel's 3 Spirits:	Subjective Spirit~ Objective Spirit~ Absolute Spirit
Plotinu's Philosophy:	One~ One Many~ One and Many
Aristotle's 3 Unities:	Unity of Action~ Unity of Time~ Unity of Place
Sir F. Bacon's 3 Tables:	Presence~ Absence~ Degree
Thomas Hobbes's 3 Fields:	Physics~ Moral Philosophy~ Civil Philosophy
Immanuel Kant's 3 Critiques:	Pure Reason~ Practical Reason~ Judgment
Averroes's 3 Commentaries:	Little~ Middle~ Great
Karl Marx's 3 isms:	Communism~ Socialism~ Capitalism
Woodrow Wilson's 3 isms:	Colonialism~ Racism~ Anti-Communism
Hippocrates's Mind Disorders:	Mania~ Melancholia~ Phrenitis
Emile Durkeim's 3 Suicides:	Egoistic~ Altruistic~ Anomic
D. Liesman's 3 Social Characters:	Tradition-directed~ Inner-directed~ Other-directed
Erich Fromm's 3 Symbols:	The Conventional~ The Accidental~ The Universal
Pythagoras's "fusion" idea:	Monarchy~ Oligarchy~ Democracy (into harmonic whole)
M.L. King Jr.'s "Middle Road":	Acquiescence~ Nonviolence~ Violence
Kierkegaard's 3 Stages:	Aesthetic~ Ethical~ Religious
Husserl's 3 Reductions:	Phenomenological~ Eidetic~ Religious
St. Augustine's 3 Laws:	Divine Law~ Natural Law~ Temporal, or positive Law
Witness Stand truths:	The Truth~ The whole Truth~ Nothing but the Truth
Titus Carus's 3 Ages:	Stone Age~ Bronze Age~ Iron Age
Feuerbach's 3 Thoughts:	God, 1st Thought~ Reason, 2nd~ Man, 3rd
Magnus's 3 Universals:	Ante Rem~ In Rem~ Post Rem
Max Weber's 3 Authorities:	Traditional~ Charismatic~ Legal-rational
F. de Sausure's 3 "Signs":	Sign~ Signified~ Signifier
Charles Peirce's 3 semiotic elements	Sign~ Object~ Interpretant
Charles Pierce's 3 categories:	Quality of feeling~ Reaction/resistance~ Representation
Charles Peirce's 3 universes of experience:	Ideas~ Brute fact~ Habit (habit-taking)
Charles Peirce's 3 normatives:	The good (esthetic)~ The right (ethical)~ The true (logical)
Charles Peirce's 3 grades of conceptual clearness	By familiarity~ Of definition's parts~ Of conceivable practical consequences
Charles Peirce's 3 modes of evolution:	Fortuitous variation~ Mechanical necessity~ Creative love
John Keynes's 3 Eras:	Scarcity~ Abundance~ Stabilization
George Mead's 3 Distinctions:	Self~ I~ Me
Thrasher's 3-group Gangs:	Inner Circle~ Rank & File~ Fringers
Abe Lincoln's 3-For-All:	Of the People~ By the People~ For the People
Jesus Christ's 3 Praises:	In the name of the Father~ Son~ Holy Spirit
Samuel Clemmons' (Mark Twain) 3 lies:	Lies~ Damned Lies~ Statistics
J.W.S. Pringle's 3 intellectual problems:	Religious & Ethical~ Practical~ Scientific
J. Bruner's 3 cognitive processing modes:	Enactive~ Iconic~ Symbolic
Wilhelm Wundt's 3 mind elements:	Sensations~ Images~ Feelings
Robert Sternberg's 3 love components:	Passion~ Intimacy~ Commitment
Sternberg's Triarchic Intelligence:	Analytic~ Creative~ Practica
Paul D. Maclean's Triune Brain:	R-System (Reptilian)~ Limbic System~ Neocortex
3-monkey Philosophy:	Hear no Evil~ See no Evil~ Speak no Evil
J.A. Fodor's mind Taxonomy:	Central Processes~ Input Processes~ Transducers
Plato's Tripartite soul:	Rational~ Libidinous~ Spirited (various animal qualities)
Hjalmar Wennerberg's philosophy orders:	Phenomenology~ Normative Science~ Metaphysics
W.H. Sheldon's body types:	Endomorph~ Mesomorph~ Ectomorph
Ernst Kretschmer's body types:	Pyknic~ Asthenic~ Athletic
Aristotle's 3 in 1 idea:	Mind~ Self-knowledge~ Self-love
K.J.W. Craik's 3 reasoning processes:	Translation~ Reasoning~ Retranslation
Galton's 3 genius traits:	Intellect~ Zeal~ Power of working
Gregor Mendel "laws":	Independent Unit Characters~ Segregation~ Dominance
Darwinian essentials of Evolution:	Variation~ Heredity~ Struggle for existence

In Education

3 R's: Reading~ 'Riting~ 'Rithmetic
3 divisions: Elementary (Grade) School~ Middle (Jr. High or Intermediate) School~ High (Sr. High) School
3 levels: Primary (~Elementary) Education~ Secondary (~Jr. + Sr. High) Education~ Tertiary (College, University, Polytechnical Institute, TAFE) Education
3 University degrees: Bachelor's~ Master's- Ph.D
3 University distinctions: Cum Laude~ Magna Cum Laude~ Suma Cum Laude
3 testing formats: True/False~ Multiple Choice~ Essay
3 levels to grade formulas: A+ (A plus)~ A (A neutral)~ A- (A minus)
3 good grade divisions: A~ B~ C
3 rings of the school bell return children to class after a fire drill.
3 ring notebooks are one standard of usage for holding looseleaf notebook paper (2 is another in lever-arch).
3-number combination locks are a standard usage for lockers.

In politics

Plato split his utopian city into three populations: laborers, guardians (warriors), and philosophers (rulers)
Several polities have been ruled by three persons in a triumvirate or a troika.
As well, medieval theory divided society in laboratores (peasants), bellatores (noble warriors) and oratores (clergy). An earlier division had only the potentes ("powerful", warriors) and the powerless.

Christ sorting people into prayers, protectors and workers.

In the Ancient Regime, the estates of the realm (e.g. the French Estates General) were divided in a branch for aristocracy, another for the Catholic hierarchy and the Third Estate for rich peasants and bourgeoisie. The triumph of the Third Estate is the French Revolution.
By analogy to the Third Estate, the Third World (poor countries or non-aligned countries) was defined as different from the First World (led by the United States) and the Second World (led by the Soviet Union).
The "third way" is a political term applied to a variety of "third choice" options that some offer as an alternative to dichotomous situations which may otherwise appear polarized.
After the fall of Constantinople, the Tsars considered Moscow as the Third Rome.
Also Nazism considered Nazi Germany the Third Reich after the Holy Roman Empire and the Prussian Empire.
There are three branches to the US government; executive, legislative, and judicial.
Alvin Toffler's The Third Wave considers that the late twentieth century saw the beginning of a third wave of change in post-industrial civilization after the Neolithic and the Industrial Revolution.
The Third International supported Leninism.
Cenocracy is the word coined to represent what is believed by some to be the next and superior step to present day forms of Democratic rule. It is based on the notion that before a society can truly achieve a government Of-By-and For the people, the people themselves must play a direct part (and not be represented vicariously) in the law-making process. To this end, every man, woman, and worker must have access to such a role, thus constituting a true 3rd branch legislative body. For example, each State in the United States would adopt an ongoing list of self-elected candidates from which the 3 aforementioned persons would be randomly selected to fulfill one-year terms of office with at least the same pay, privileges and legislative power commensurate to all other congressional members.

As a lucky or unlucky number

Three (三, formal writing: 叁, pinyin san1, Cantonese: saam1) is considered a good number in Chinese culture because it sounds like the word "alive" (生 pinyin sheng1, Cantonese: saang1), compared to four (四, pinyin: si4, Cantonese: sei3) that sounds like the word "death" (死 pinyin si3, Cantonese: sei2).

Counting to three is common in situations where a group of people wish to perform an action in synchrony: Now, on the count of three, everybody pull! Assuming the counter is proceeding at a uniform rate, the first two counts are necessary to establish the rate, but then everyone can predict when "three" will come based on "one" and "two"; this is likely why three is used instead of some other number.

In Vietnam, it is bad luck to take a photo with three people in it.

Luck, especially bad luck, is often said to "come in threes".

Some cultures in history have a place for people of third gender such as in Thailand.

It is often believed that people die in threes. This only includes people in your personal sphere (ie. directly impact on your day-to-day life).

There is a superstition that states it is unlucky to take a third light, that is, to be the third person to light a cigarette from the same match or lighter. This is commonly believed to date from the trenches of the First World War when a sniper might see the first light, take aim on the second and fire on the third.

3 strikes and you're out.

3rd time's a charm.

In technology

3 as a resin identification code, used in recycling.

The resin identification code used in recycling to identify polyvinyl chloride.
On computer keyboards, in the United Kingdom the "3" key may be used to type the pound sign when pressed in combination with the shift key.
On most telephone keypads, the "3" key is also associated with the letters "D", "E", and "F".
In ASCII, the code for "3" in hexadecimal is 33. This is the only character in ASCII such that a large file consisting of a single character has identical-looking hexadecimal and normal representation.

The glyph "3" may be used as a substitute for yogh (Ȝ, ȝ) or ze (З, з) when those characters are not available.
Three is the minimum odd number of voting components for simple easy redundancy checks by direct comparison.
Three is approximately pi (actually closer to 3.14159) when doing rapid engineering wags or estimates. The same is true if one wants a rough-and-ready estimate of e, which is actually approximately 2.7183.
Some computer users may use "3" as an alternate to the letter "E", often in jest or to prevent search engines from reading their messages. This form of code is an example of basic Leetspeak.
"3" is the DVD region code for many East Asian countries, except for Japan (which is Region 2) and China (which is Region 6).

In music

In music, the Roman numeral iii is the mediant scale degree, chord, or diatonic function, when distinguished III = major and iii = minor.

Three is the number of performers in a trio.

There are 3 notes in a triad, the most important and basic form of any chord.

Any diatonic chord progression's key signature is made obvious with any 3 different triads, as opposed to potential key ambiguities with any 2 chords.

The tritone, which divides the octave into 3 equally spaced notes (root, tritone, octave) is the rarest interval of any mode, only occurring semantically twice, and physically once. It is the only interval that, when inverted, remains unchanged functionally and harmonically.

The 3/4 time signature of Western classical music tradition (Three beats to a measure, with the quarter note comprising the beat.) is said to represent the Holy Trinity of Christian doctrine, Father, Son and Holy Spirit. It is for this reason that it is often utilized in compositions which were written for use in ecclesiastical rites, or that are inspired by scriptural/spiritual themes and texts.

In a standard jazz combo there are 3 necessary parts: bass, percussion, and chord maker.

3 is The Magic Number according to De La Soul.

In Geography

Several cities are known as Tripoli from Greek for "three cities".
Sicilia was known as Trinacria for its triangle-shape.
Three Mile Island is known for a nuclear accident.

In filmography

Three is a 1969 film starring Charlotte Rampling and Sam Waterston.
Three is a 1965 Yugoslavian film directed by Aleksandar Petrović.
Three is a 2002 Asian horror movie collaboration.
Thr3e is a 2007 film adaptation of the novel of the same name by Ted Dekker.
Three, also known as Survival Island is a 2006 film starring Billy Zane and Kelly Brook.
There is a 1977 film titled 3 Women.
In both the film The Craft and the fantasy television series Charmed, the "power of three" has been used as part of wiccan incantations.
The Three Stooges, a comedy group made up of "Larry, Moe, and Curly" and later "Larry, Moe, and Shemp" in the early- to mid-20th century.

In sports

In Bowling, 3 strikes in a row is called a turkey.
In Cricket, 3 outs in a row is called a hat trick.
In ice hockey, a game consists of 3 periods of twenty minutes each.
In rugby union, 3 is the jersey number of the starting tighthead prop. It is also the number of points received for a successful drop goal or penalty kick.
In baseball, 3 is the number of strikes before the batter is out and the number of outs per side per inning. It also represents the first baseman's position. The number 3 position in the batting order is generally occupied by the team's best hitter. In high school and college, 3 is the maximum "drop" (inches of length minus ounces of weight) for a legal bat. 3 is the retired number of Baseball Hall of Fame players Babe Ruth, Joe Medwick, Bill Terry, and Harmon Killebrew. Gary Sheffield and Ken Griffey Jr wear the number three.
In basketball, a shot made from behind the three-point arc is worth 3 points. 3 is used to represent the small forward position.
Is the number of the famous NASCAR stock car that Dale Earnhardt drove for nearly 20 years before his death in 2001. He won 6 out of his 7 championships while driving the #3 car. No one has driven the 3 car since his death. In IROC, Helio Castroneves had his car number changed from his standard 3 (which he drives in the Indy Racing League) to number 03.
Traditional number for the Tyrrell Formula One team's first car along with number 4 for the second until the end of the 1995 Formula One Season.
A hat-trick in sports is associated with succeeding at anything three times in three consecutive attempts.
In both American and Canadian football, the number of points received for a successful field goal.
In Canadian football, the last down before a team loses possession on downs. Usually, a team faced with a third down will punt (if far from the opponent's goal line) or attempt a field goal (if relatively close).
An Ironman triathlon consists of three events, a 2.4 mile (3.86 kilometer) swim, a 112 mile (180.2 kilometer) bike ride, and a 26.2 mile (42.2 kilometer) marathon run.
In football, number 3 is assigned in most cases to the left defender or fullback.
On March 24, 2006 the number 3 became the second number retired by the New Jersey Devils in honor of defenseman Ken Daneyko.

In literature

3 is the number of words or phrases in a Tripartite motto.
3 is the number of novels or films in a trilogy and the number of interconnected works of art in a triptych.
The tricolon is often used for rhetorical effect.
Thr3e is a 2003 suspense novel written by Thriller author Ted Dekker.
Dante Alighieri's Divine Comedy has three parts each of thirty-three cantos (plus one introductory canto totaling 100). It was written in terza rima, a combination of tercets. All of this is an allusion to the Christian Trinity.
The number three recurs several times in Tolkien's The Lord of the Rings and also in The Silmarillion. Three Rings of Power were given to the Elves. There are three Silmarils. The unions of the Eldar (Elves) and the Edain (Men) were three in number: Beren and Lúthien, Tuor and Idril, and (of course) Aragorn and Arwen.
Three Blind Mice is a children's nursery rhyme and musical round.
The Three Musketeers is a novel by Alexandre Dumas, and is part of a trilogy.
The Three Sisters is a play by Anton Chekhov.

Original scholarly articles/reviews about the three

The Number Three in The American Culture. A selected chapter found in the book entitled "Every Man His Way" (1967- 68) by Alan Dundes.

"People in Threes Going Up in Smoke and Other Triplicities in Russian Literature and Culture" (Fall 2005, Rocky Mountain Review) by Lee B. Croft.

"Buckland's Third Revolution" (1997- 98) and "Three Wise Men" (1984 - 85) posters by Herb O. Buckland.

In other fields

Three is:

Three are the values of French Revolution (liberty, equality, fraternity) , and the colors of French flag. Colombian flag has three colors, meaning Gold, Water and Blood.
Three is a mobile phone operator.
The number of stars in "Pacific's triple star" in the God Defend New Zealand, one of New Zealand's two national anthems.
The phrase "Third time's the charm" (or, rarely, "Three time's the charm") usually means that the third time a person attempts something, he or she will succeed
Three-bean salad is an appetizer containing three types of beans, such as kidney, yellow, and green beans.
In most earlier video games, three lives were commonly given to players at the start.
The television VHF channel most often used for hooking up VCRs and/or video game systems. If it is otherwise occupied by a local broadcaster, then channel 4 is used instead.
On most phones, the 3 key is associated with the letters D, E, and F, but on the BlackBerry it is the key for U and I.
"In Memory of 3" - a phrase about NASCAR driver Dale Earnhardt, who drove the number 3 car. It can also refer to a 2004 ESPN television movie about Earnhardt's life called, 3: The Dale Earnhardt Story.
No. 3 - 1997 Korean gangster comedy written and directed by Neung-han Song
In Astrology, Gemini is the 3rd astrological sign of the Zodiac.
The number 3 is often used as a literary device to provoke a feeling of unnaturalness, as twos are much more common in nature (limbs, hemispheres, eyes, etc). This is a prevailing theme in Ray Bradbury's novel Fahrenheit 451. The aliens and their machines in the 2005 film War of the Worlds were associated with features recurring in threes: eyes, legs, fingers, etc, for this same reason.
Threesome is a term for sexual relations between three people.
A tricycle has three wheels.
The standard number of lives in many arcade video games, such as Pac-Man, Sonic the Hedgehog and Mega Man.^{[citation needed]}
In Archeology- three Giza Pyramids: Khufu, Khafre, and Menkaure (Giza pyramid complex).

References

^ Georges Ifrah, The Universal History of Numbers: From Prehistory to the Invention of the Computer transl. David Bellos et al. London: The Harvill Press (1998): 393, Fig. 24.63

Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group. (1987): 46 - 48

External links

Tricyclopedic Book of Threes by Michael Eck
Three at IMDb
Threes in Human Anatomy by Dr. John A. McNulty

[1] Georges Ifrah, The Universal History of Numbers: From Prehistory to the Invention of the Computer transl. David Bellos et al. London: The Harvill Press (1998): 393, Fig. 24.63

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