Sudoku (数独, sūdoku, digit-single) (/sˈdk/, /-ˈdɒ-/, /sə-/; originally called Number Place), is a logic-based, combinatorial number-placement puzzle. The objective is to fill a 9×9 grid with digits so that each column, each row, and each of the nine 3×3 sub-grids that compose the grid (also called "boxes", "blocks", "regions", or "sub-squares") contains all of the digits from 1 to 9. The puzzle setter provides a partially completed grid, which for a well-posed puzzle has a unique solution.

Completed puzzles are always a type of Latin square with an additional constraint on the contents of individual regions. For example, the same single integer may not appear twice in the same row, column or in any of the nine 3×3 subregions of the 9x9 playing board.
French newspapers featured variations of the puzzles in the 19th century, and the puzzle has appeared since 1979 in puzzle books under the name Number Place. However, the modern

sudoku only started to become mainstream in 1986 by the Japanese puzzle company Nikoli, under the name Sudoku, meaning single number. It first appeared in a US newspaper and then The Times (UK) in 2004, from the efforts of Wayne Gould, who devised a computer program to rapidly produce distinct puzzles.

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  • 1. [Kakuro] Kakuro or Kakkuro (Japanese: カックロ) is a kind of logic puzzle that is often referred to as a mathematical transliteration of the crossword. Kakuro puzzles are regular features in many math-and-logic puzzle publications in the United States. In 1966, Canadian Jacob E. Funk, an employee of Dell Magazines came up with the original English name
  • 2. [Crossword] A crossword is a word puzzle that normally takes the form of a square or a rectangular grid of white and black shaded squares. The goal is to fill the white squares with letters, forming words or phrases, by solving clues which lead to the answers. In languages that are written left-to-right, the answer words and phrases are placed in the grid from left to right and from top to bottom. The shaded squares are used to separate the words or phrases.
  • 3. [Logic puzzle] A logic puzzle is a puzzle deriving from the mathematics field of deduction.
  • 4. [Nonogram] Nonograms, also known as Hanjie, Picross or Griddlers, are picture logic puzzles in which cells in a grid must be colored or left blank according to numbers at the side of the grid to reveal a hidden picture. In this puzzle type, the numbers are a form of discrete tomography that measures how many unbroken
  • 5. [KenKen] KenKen and KenDoku are trademarked names for a style of arithmetic and logic puzzle invented in 2004 by Japanese math teacher Tetsuya Miyamoto, who intended the puzzles to be an instruction-free method of training the brain. The names Calcudoku and Mathdoku are sometimes used by those who don't have the rights to use the KenKen or KenDoku trademarks.
  • 6. [Puzzle] A puzzle is a game, problem, or toy that tests a person's ingenuity or knowledge. In a puzzle, one is required to put pieces together in a logical way, in order to arrive at the correct solution of the puzzle. There are different types of puzzles for different ages, such as crossword puzzles, word-search puzzles, number puzzles, or logic puzzles.
  • 7. [World Puzzle Championship] The World Puzzle Championship (commonly abbreviated as WPC) is an annual international puzzle competition run by the World Puzzle Federation. All the puzzles in the competition are pure-logic problems based on simple principles, designed to be playable regardless of language or culture.
  • 8. [Howard Garns] Howard Garns (March 2, 1905 – October 6, 1989) was an American architect who gained fame only after his death as the creator of Number Place, the number puzzle that became a worldwide phenomenon under the name Sudoku.
  • 9. [World Sudoku Championship] The World Sudoku Championship is an annual international sudoku competition organised by a member of the World Puzzle Federation. The first one was held in Lucca in 2006. National teams are determined by local affiliates of the World Puzzle Federation. The competition typically consists of 50 or more puzzles solved by all competitors over multiple
  • 10. [Nikoli] Nikoli (ニコリ, nikori) Co., Ltd. is a Japanese publisher that specializes in games and, especially, logic puzzles. Nikoli is also the nickname of a quarterly magazine (whose full name is Puzzle Communication Nikoli) issued by the company in Tokyo. Nikoli was established in 1980 and became prominent worldwide with the popularity of Sudoku.
  • 11. [Futoshiki] Futoshiki (不等式, futōshiki), or More or Less, is a logic puzzle game from Japan. Its name means "inequality". It is also spelled hutosiki (using Kunrei-shiki romanization).
  • 12. [Latin square] In combinatorics and in experimental design, a Latin square is an n × n array filled with n different symbols, each occurring exactly once in each row and exactly once in each column. Here is an example:
  • 13. [Thomas Snyder] Thomas Snyder (born c. 1980) is an American puzzle creator and world-champion sudoku solver. He writes a puzzle blog as Dr. Sudoku.
  • 14. [Mathematics of Sudoku] The class of Sudoku puzzles consists of a partially completed row-column grid of cells partitioned into N regions each of size N cells, to be filled in using a prescribed set of N distinct symbols (typically the numbers {1, ..., N}), so that each row, column and region contains exactly one of each element of the set. The puzzle can be investigated using mathematics.
  • 15. [Pentomino] A pentomino is a plane geometric figure formed by joining five equal squares edge to edge. It is a polyomino with five cells. There are twelve pentominoes, not counting rotations and reflections as distinct. They are used chiefly in recreational mathematics for puzzles and problems. Pentominoes were formally defined by American professor Solomon W. Golomb
  • 16. [Dancing Links] In computer science, dancing links, also known as DLX, is the technique suggested by Donald Knuth to efficiently implement his Algorithm X. Algorithm X is a recursive, nondeterministic, depth-first, backtracking algorithm that finds all solutions to the exact cover problem. Some of the better-known exact cover problems include tiling, the n queens problem, and Sudoku.
  • 17. [Glossary of Sudoku] This is a glossary of Sudoku terms and jargon.

  • 18. [Hidato] Hidato (Hebrew: חידאתו‎, originating from the Hebrew word Hida = Riddle) is a logic puzzle game invented by Dr. Gyora Benedek, an Israeli mathematician. The goal of Hidato is to fill the grid with consecutive numbers that connect horizontally, vertically, or diagonally. Numbrix puzzles, created by Marilyn vos Savant, are similar to Hidato except that
  • 19. [Hebdomada Aenigmatum] Hebdomada Aenigmatum is the first magazine of crosswords and puzzles in Latin.
    It is published monthly by the Italian cultural association Leonardo, in collaboration with the online Latin news magazine Ephemeris and with ELI publishing house. It is available free of charge in printable pdf format upon registration on the website.
  • 20. [Rubik's Cube] Rubik's Cube is a 3-D combination puzzle invented in 1974 by Hungarian sculptor and professor of architecture Ernő Rubik. Originally called the Magic Cube, the puzzle was licensed by Rubik to be sold by Ideal Toy Corp. in 1980 via businessman Tibor Laczi and Seven Towns founder Tom Kremer, and won the German Game of
  • 21. [Magic square] In recreational mathematics, a magic square is an arrangement of distinct numbers (i.e. each number is used once), usually integers, in a square grid, where the numbers in each row, and in each column, and the numbers in the main and secondary diagonals, all add up to the same number. A magic square has the
  • 22. [Barnes & Noble Nook] The Barnes & Noble Nook (styled "nook" or "NOOK") is a brand of e-readers developed by American book retailer Barnes & Noble, based on the Android platform. The original device was announced in the United States in October 2009, and was released the next month. The original Nook was capable of Wi-Fi and AT&T 3G
  • 23. [36 Cube] The 36 Cube is a three-dimensional sudoku puzzle created by ThinkFun. The puzzle consists of a gray base that resembles a city skyline, plus 36 colored towers. The towers come in six different colors and six different heights. The goal of the puzzle is to place all the towers onto the base so as to
  • 24. [SUDO-Q] SUDO-Q was a game show that was broadcast between 5 December 2005 and 23 March 2007. It was hosted by Eamonn Holmes. The format was based on a mix of the number puzzle Sudoku and general knowledge questions.
  • 25. [Heptomino] A heptomino (or 7-omino) is a polyomino of order 7, that is, a polygon in the plane made of 7 equal-sized squares connected edge-to-edge. The name of this type of figure is formed with the prefix hept(a)-. When rotations and reflections are not considered to be distinct shapes, there are 108 different free heptominoes. When
  • 26. [La France (French newspaper)] La France was a daily financial newspaper in the 19th century. Founded in August 1862 by Arthur de La Guéronnière, the newspaper originally followed an editorial line that reconciled loyalty to Napoleon III with the reaffirmation of the temporal power of the Pope. It was bought in 1874 by Émile de Girardin, founder of the famous newspaper La Presse and a longtime collaborator of La Guéronnière.
  • 27. [Dell Magazines] Dell Magazines was a company founded by George T. Delacorte Jr. in 1921 as part of his Dell Publishing Co. Dell is today known for its many puzzle magazines, as well as fiction magazines such as Alfred Hitchcock's Mystery Magazine, Ellery Queen's Mystery Magazine, Asimov's Science Fiction, and Analog Science Fiction and Fact. It was
  • 28. [NP-completeness] In computational complexity theory, a decision problem is NP-complete when it is both in NP and NP-hard. The set of NP-complete problems is often denoted by NP-C or NPC. The abbreviation NP refers to "nondeterministic polynomial time".
  • 29. [Wei-Hwa Huang] Wei-Hwa Huang (黃煒華, born August 4, 1975) is an award-winning American puzzler, member of the US Team for the World Puzzle Championship, and game designer.
  • 30. [Broken diagonal] In recreational mathematics and the theory of magic squares, a broken diagonal is a set of n cells forming two parallel diagonal lines in the square. Alternatively, these two lines can be thought of as wrapping around the boundaries of the square to form a single sequence. A magic square in which the broken diagonals have the same sum as the rows, columns, and diagonals is called a panmagic square.
  • 31. [Constraint satisfaction problem] Constraint satisfaction problems (CSPs) are mathematical problems defined as a set of objects whose state must satisfy a number of constraints or limitations. CSPs represent the entities in a problem as a homogeneous collection of finite constraints over variables, which is solved by constraint satisfaction methods. CSPs are the subject of intense research in both
  • 32. [Set (game)] Set is a real-time card game designed by Marsha Falco in 1974 and published by Set Enterprises in 1991. The deck consists of 81 cards varying in four features: number (one, two, or three); symbol (diamond, squiggle, oval); shading (solid, striped, or open); and color (red, green, or purple). Each possible combination of features (e.g., a card with three striped green diamonds) appears precisely once in the deck.
  • 33. [The Conway Daily Sun] The Conway Daily Sun is a five-day (Tuesday through Saturday) free daily newspaper published in the town of Conway, New Hampshire, U.S., covering the Mount Washington Valley. It has been published since 1989 by Country News Club, and was the forerunner of three other Daily Sun newspapers in New Hampshire and Maine.
  • 34. [Connersville, Indiana] Connersville is a third class city in Fayette County, east central Indiana, United States, 66 miles east by southeast of Indianapolis. The population was 13,481 at the 2010 census. The city is the county seat of and the largest and only incorporated town in Fayette County. It is home to the county's one and only
  • 35. [Carol Vorderman] Carol Jean Vorderman MBE RAFVR(T) (born 24 December 1960) is a British media personality, best known for co-hosting the popular game show Countdown for 26 years from 1982 until 2008.
  • 36. [NRC Handelsblad] NRC Handelsblad (Dutch pronunciation: [ɛnɛrseː ˈɦɑndəlzblɑt]), often abbreviated to NRC, is a daily evening newspaper published in the Netherlands by NRC Media.
  • 37. [Rotational symmetry] Generally, an object with 'rotational symmetry' also known in biological contexts as 'radial symmetry', is an object that looks the same after a certain amount of rotation. An object may have more than one rotational symmetry; for instance, if reflections or turning it over are not counted. The degree of rotational symmetry is how many degrees the shape has to be turned to look the same on a different side or vertex. It cannot be the same side or vertex.
  • 38. [Žilina] Žilina (Slovak pronunciation: [ˈʒilina]; German: Sillein, [ziˈlaɪ̯n] or [ˈzɪlaɪ̯n]; Hungarian: Zsolna; Polish: Żylina, names in other languages) is a city in north-western Slovakia, around 200 kilometres (120 mi) from the capital Bratislava, close to both the Czech and Polish borders. It is the fourth largest city of Slovakia with a population of approximately 85,000, an
  • 39. [App Store (iOS)] The App Store is a digital distribution platform for mobile apps on iOS, developed and maintained by Apple Inc. The service allows users to browse and download applications that are developed with Apple's iOS SDK. The apps can be downloaded directly to iOS devices such as the iPhone smartphone, the iPod Touch handheld computer and the iPad tablet computer, or onto a personal computer via iTunes.
  • 40. [Quincunx] A quincunx /ˈkwɪn.kʌŋks/ is a geometric pattern consisting of five points arranged in a cross, with four of them forming a square or rectangle and a fifth at its center. It forms the arrangement of five units in the pattern corresponding to the five-spot on six-sided dice, playing cards, and dominoes. It is represented in
  • 41. [Nintendo DS] The Nintendo DS (ニンテンドーDS, Nintendō DS) is a dual-screen handheld game console developed and released by Nintendo. The device went on sale in North America on November 21, 2004. The DS, short for "Developers' System" or "Dual Screen", introduced distinctive new features to handheld gaming: two LCD screens working in tandem (the bottom
  • 42. [IPhone] iPhone (/ˈfn/ EYE-fohn) is a line of smartphones designed and marketed by Apple Inc. They run Apple's iOS mobile operating system. The first generation iPhone was released on June 29, 2007; the most recent iPhone models are the iPhone 6s and iPhone 6s Plus, which were unveiled at a special event on September 9, 2015.
  • 43. [Teletext] Teletext (or broadcast teletext) is a television information retrieval service created in the United Kingdom in the early 1970s by the Philips Lead Designer for VDUs, John Adams. Teletext is a means of sending pages of text and simple geometric shapes from mosaic blocks to a VBI decoder equipped television screen by use of a
  • 44. [Symmetry] Symmetry (from Greek συμμετρία symmetria "agreement in dimensions, due proportion, arrangement") in everyday language refers to a sense of harmonious and beautiful proportion and balance. In mathematics, "symmetry" has a more precise definition, that an object is invariant to a transformation, such as reflection but including other transforms too. Although these two meanings of "symmetry" can sometimes be told apart, they are related, so they are here discussed together.
  • 45. [Entropy (information theory)] In information theory, systems are modeled by a transmitter, channel, and receiver. The transmitter produces messages that are sent through the channel. The channel modifies the message in some way. The receiver attempts to infer which message was sent. In this context, entropy (more specifically, Shannon entropy) is the expected value (average) of the information contained in each message. 'Messages' can be modeled by any flow of information.
  • 46. [Matrix (mathematics)] In mathematics, a matrix (plural matrices) is a rectangular array—of numbers, symbols, or expressions, arranged in rows and columns—that is interpreted and manipulated in certain prescribed ways. One such way is to state the dimensions of the matrix. For example, the dimensions of the matrix below are 2 × 3 (read "two by three"), because there are two rows and three columns.
  • 47. [Daily Mail] The Daily Mail is a British daily middle-market tabloid newspaper owned by the Daily Mail and General Trust.
    First published in 1896 by Lord Northcliffe, it is the United Kingdom's second biggest-selling daily newspaper after The Sun. Its sister paper The Mail on Sunday was launched in 1982. Scottish and Irish editions of the daily paper
  • 48. [IPod] The iPod is a line of portable media players and multi-purpose pocket computers designed and marketed by Apple Inc. The first line was released on October 23, 2001, about 8½ months after iTunes (Macintosh version) was released. The most recent iPod redesigns were announced on July 15, 2015. There are three current versions of the iPod: the ultra-compact iPod Shuffle, the compact iPod Nano and the touchscreen iPod Touch.
  • 49. [PlayStation Portable] The PlayStation Portable (officially abbreviated as PSP) is a handheld game console developed by Sony. Development of the console was announced during E3 2003, and it was unveiled on May 11, 2004, at a Sony press conference before E3 2004. The system was released in Japan on December 12, 2004, in North America on March
  • 50. [Brentford]
    Brentford is a town in west London, England and part of the London Borough of Hounslow, at the confluence of the River Brent and the Thames, 8 miles (13 km) west-by-southwest of Charing Cross. It has formed part of Greater London since 1965.
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