Main Page | See live article | Alphabetical index ''For the year AD 3, see 3. Three (3) is the natural number following two and preceding four. Table of contents 1 Properties of three 2 Three-ness in human culture 3 More references to groups of three 4 Chemicals 5 Other references to three Properties of three Three is the second smallest prime number, the next is five. Three is the second triangular number. Three is the first Fermat prime. Three is a Fibonacci number (And it is the third different one, too!). Fractions with 3 in the denominator have a single digit repeating sequences in their decimal expansions, (.000…, .333… or .666…) A natural number is divisible by three if and only if its decimal digit sum is divisible by 3. The base-3 numeral system is the ternary system. Three-ness in human culture Many human cultures have given the concept of three-ness symbolic meanings: The Holy Trinity in Christian doctrine (or trinity in general) The process of synthesis in Hegelianian dialectic creates three-ness from two-ness The three Doshas (weaknesses) and their antidotes are the basis of Ayurvedic medicine in India The three Gunas underlie action, in the Vedic system of knowledge The Trimurti in Hindu tradition Three (三 pinyin san1) is considered a good number in Chinese culture because it sounds like the word "alive" (生 pinyin sheng1), compare to four More references to groups of three 3-D Three-decker - a ship of three decks Three-spine stickleback - a type of fish Three-toed woodpecker Threepence - three-penny coin Threesome - trio or else Thrice - three times Triad - a group of three Trialogue - conversation among three Triangle - polygon with three sides Triangulation Triangulum and Triangulum Australe - constellations Triarchy - government of three Triassic Period - geologic time Triathlete - contestant in Triathlon Triathlon - contest in three sports Tribrach - metrical foot, in poetry Triceps - a muscle Triceratops - a dinosaur Trichotomy - division into three parts Trichroism - property of minerals such as tanzanite, andalusite and iolite Trichromatism - of three-color technology or perception Triclinium - a couch to three sides of table Tricolor - three-color flag, as in France, Romania, Moldova Tricorn - of three corners, e.g., a hat with "tricorned brim" Tricuspid - of three cusps Tricycle - (bicycle × 1½) Tridactyl - of three toes Trident - of three teeth or prongs Triennium - three-year time Trierarch - captain or manager of a trireme Trifid - cleft into three Trifocal - a lens (e.g., of eyeglasses) with three focal lengths Trifoliate - a leaf structure Triforium - a certain gallery in church Trifurcate - threeforked or threestemmed Trigeminus - trigeminal nerve Triglyph - an ornament Trigon - triangular harp Trigonometry - a branch of mathematics Trigram - I Ching thing Trigraph - three-letter combination Trihedron - afigure of three meeting planes Trihybrid - a kind of hybrid Trilateral - of three sides or parties Trilingual - able of or expressed in three languages Triliteral - a word or root of three letters Trilithon - prehistoric three-stone structure Trillion - 1012 (American) 1018 (British) Trilobate - of three lobes Trilobite - a marine arthropod Trilogy - three works on a theme under the same authorship Trio - three musicians or three actors Tripartition - division into three parts Tripod - a three-legged structure Trireme Triumvirate - government of three Trivium - grammar+logic+rhetoric ("three roads") Troika Chemicals Triacid, Triaminic, Triamcinolone, Triazine, Triazole, Tribromoethanol, Trichloroethylene, Trichlorfon, Trifluralin, Triglyceride, Triglycerophosphate, Triphosphopyridine nucleotide Other references to three "In Memory of 3" - a phrase about NASCAR driver Dale Earnhardt No. 3 - 1997 Korean gangster comedy written and directed by Neung-han Song 3 - a rock band formed by Keith Emerson, Robert Berry and Carl Palmer Three Kingdoms Three Gorges Three-letter abbreviations and acronyms Three links Three of a kind - in poker Three Principles of the People Three Represents Three's Company - an American sitcom Three Years of Natural Disasters See also: one, two, three, four, five, integer, list of numbers. This article is from Wikipedia. All text is available under the terms of the GNU Free Documentation License.