However, the modern Sudoku only began to gain widespread popularity in 1986 when it was published by the Japanese puzzle company Nikoli under the name Sudoku, meaning
 Garns’s name was always present on the list of contributors in issues of Dell Pencil Puzzles and Word Games that included Number Place, and was always absent from issues
that did not.
French newspapers featured variations of the Sudoku puzzles in the 19th century, and the puzzle has appeared since 1979 in puzzle books under the name Number Place.
‘digit-single’; originally called Number Place) is a logic-based, combinatorial number-placement puzzle.
The Times also publishes a three-dimensional version under the name Tredoku.
Some variants, such as in the TV Guide Magazine, include a word reading along a main diagonal, row, or column once solved; determining the word in advance can be viewed as
a solving aid.
An example of Greater Than Sudoku A tabletop version of Sudoku can be played with a standard 81-card Set deck (see Set game).
Hyper Sudoku / Windoku Hypersudoku puzzle And its solution Hyper Sudoku or Windoku uses the classic 9×9 grid with 3×3 regions, but defines four additional interior 3×3
regions in which the numbers 1–9 must appear exactly once.
 It first appeared in a U.S. newspaper, and then The Times (London), in 2004, thanks to the efforts of Wayne Gould, who devised a computer program to rapidly produce unique
 Recognizing the different psychological appeals of easy and difficult puzzles, The Times introduced both, side by side, on June 20, 2005.
In this, a 3×3 grid of the Sudoku is given with 12 symbols of Greater Than (>) or Less Than (
<) on the common line of the two adjacent numbers.
 Modern Sudoku The modern Sudoku was most likely designed anonymously by Howard Garns, a 74-year-old retired architect and freelance puzzle constructor from Connersville,
Indiana, and first published in 1979 by Dell Magazines as Number Place (the earliest known examples of modern Sudoku).
The maximum number of clues that can be provided while still not rendering a unique solution is four short of a full grid (77); if two instances of two numbers each are missing
from cells that occupy the corners of an orthogonal rectangle, and exactly two of these cells are within one region, the numbers can be assigned two ways.
In classic Sudoku, the objective is to fill a 9 × 9 grid with digits so that each column, each row, and each of the nine 3 × 3 subgrids that compose the grid (also called
“boxes”, “blocks”, or “regions”) contain all of the digits from 1 to 9.
The relationship between the two theories is known, after it was proven that a first-order formula that does not mention blocks is valid for Sudoku if and only if it is valid
for Latin squares.
 Due to its popularity, Nintendo made a second Brain Age game titled Brain Age2, which has over 100 new Sudoku puzzles and other activities.
The center cell in each 3×3 grid of all nine puzzles is left blank and form a tenth Sudoku puzzle without any cell completed; hence, “clueless”.
History Predecessors Number puzzles appeared in newspapers in the late 19th century, when French puzzle setters began experimenting with removing numbers from magic
 It was not a Sudoku because it contained double-digit numbers and required arithmetic rather than logic to solve, but it shared key characteristics: each row, column and
subsquare added up to the same number.
A completed Sudoku grid is a special type of Latin square with the additional property of no repeated values in any of the nine blocks (or boxes of 3×3 cells).
 The rapid rise of Sudoku in Britain from relative obscurity to a front-page feature in national newspapers attracted commentary in the media and parody (such as when
The Guardian’s G2 section advertised itself as the first newspaper supplement with a Sudoku grid on every page).
 Mini Sudoku Under the name “Mini Sudoku”, a 6×6 variant with 3×2 regions appears in the American newspaper USA Today and elsewhere.
Often, the limit takes the form of an extra “dimension”; the most common is to require the numbers in the main diagonals of the grid to also be unique.
Over six years, he developed a computer program to produce unique puzzles rapidly.
One of the most popular video games featuring Sudoku is Brain Age: Train Your Brain in Minutes a Day!.
 The world’s first live TV Sudoku show, July 1, 2005, Sky One The world’s first live TV Sudoku show, Sudoku Live, was a puzzle contest first broadcast on July 1, 2005,
on Sky One.
A similar form, for younger solvers of puzzles, called “The Junior Sudoku”, has appeared in some newspapers, such as some editions of The Daily Mail.
 Various other grid sizes have also been enumerated—see the main article for details.
Dell Magazines regularly publishes 16×16 “Number Place Challenger” puzzles (using the numbers 1–16 or the letters A-P).
Later in 2005, the BBC launched SUDO-Q, a game show that combined Sudoku with general knowledge.
The aforementioned “Number Place Challenger” puzzles are all of this variant, as are the Sudoku X puzzles in The Daily Mail, which use 6×6 grids.
Each player had a hand-held device for entering numbers corresponding to answers for four cells.
The puzzle setter provides a partially completed grid, which for a well-posed puzzle has a single solution.
Thomas Snyder repeated as the individual overall champion, and also won the first ever Classic Trophy (a subset of the competition counting only classic Sudoku).
 Knowing that British newspapers have a long history of publishing crosswords and other puzzles, he promoted Sudoku to The Times in Britain, which launched it on November
12, 2004 (calling it Su Doku).
 In the 2009 event, the third-place finalist in the advanced division, Eugene Varshavsky, performed quite poorly onstage after setting a very fast qualifying time on paper,
which caught the attention of organizers and competitors including past champion Thomas Snyder, who requested organizers reconsider his results due to a suspicion of cheating.
The first time it was called Hyper Sudoku was in Will Shortz’s Favorite Sudoku Variations (February 2006).
Although they were unmarked, each 3×3 subsquare did indeed comprise the numbers 1–9, and the additional constraint on the broken diagonals led to only one solution.
Unlike the number of complete Sudoku grids, the number of minimal 9×9 Sudoku puzzles is not precisely known.
The Baltimore Sun and the Toronto Star publish a puzzle of this variant (titled High Five) in their Sunday edition.
Nine teams of nine players (with one celebrity in each team) representing geographical regions competed to solve a puzzle.
[‘Grossman, Lev (March 11, 2013). “The Answer Men”. Time. New York. Archived from the original on March 1, 2013. Retrieved March 4, 2013.(registration required)
o ^ Arnoldy, Ben. “Sudoku Strategies”. The Christian Science Monitor.
o ^ Schaschek, Sarah
(March 22, 2006). “Sudoku champ’s surprise victory”. The Prague Post. Archived from the original on August 13, 2006. Retrieved February 18, 2009.
o ^ Lawler, E. L. (1985). The Traveling Salesman Problem: A Guided Tour of Combinatorial Optimization.
West Sussex: John Wiley & Sons. ISBN 0-471-90413-9.
o ^ Jump up to:a b c Smith, David (May 15, 2005). “So you thought Sudoku came from the Land of the Rising Sun …” The Observer. Retrieved June 13, 2008. The puzzle gripping the nation actually
began at a small New York magazine
o ^ Hayes, Brian (2006). “Unwed Numbers”. American Scientist. 94 (1): 12–15. doi:10.1511/2006.57.3475.
o ^ Boyer, Christian (May 2006). “Supplément de l’article “Les ancêtres français du sudoku”” (PDF). Pour
la Science (in French): 1–6. Archived from the original (PDF) on December 10, 2006. Retrieved August 3, 2009.
o ^ Boyer, Christian (2007). “Sudoku’s French ancestors” (in French). (personal webpage). Archived from the original on October 10, 2007.
Retrieved August 3, 2009.
o ^ Malvern, Jack (June 3, 2006). “Les fiendish French beat us to Su Doku”. Times Online. London. Retrieved September 16, 2006.
o ^ Jump up to:a b c d e Pegg, Ed Jr. (September 15, 2005). “Ed Pegg Jr.’s Math Games: Sudoku
Variations”. MAA Online. The Mathematical Association of America. Retrieved October 3, 2006.
o ^ “Reg. No. 5056856”. Japanese Trademark 5056856. Japan Platform for Trademark Information. Retrieved October 3, 2018.
o ^ “Letters”. Timesonline.co.uk.
November 14, 2004. (subscription required)
o ^ Devlin, Keith (January 28–29, 2012). “The Numbers Game (book review of Taking Sudoku Seriously by Jason Rosenhouse et al.)”. The Wall Street Journal. Weekend Edition. p. C5.
o ^ “G2, home of the discerning
Sudoku addict”. The Guardian. London. May 13, 2005. Retrieved September 16, 2006.
o ^ “Correction attached to “Inside Japan’s Puzzle Palace””. The New York Times. March 21, 2007.
o ^ “Sudoku the song, by Peter Levy”. Sudoku.org.uk. August 17,
2006. Retrieved October 5, 2008.
o ^ “Hit Song Has the Numbers”. The Herald Sun. August 17, 2006. Retrieved October 5, 2008.
o ^ “Brain Age: Train Your Brain in Minutes a Day!”. Gamerankings.com.
o ^ “Brain Age: … Review”. Gamespot.com.
“Brain Age: … Review” Archived August 11, 2012, at the Wayback Machine. IGN.com.
o ^ Thorsen, Tor (October 26, 2006). “Nintendo posts $456.6 million profit”. GameSpot. Retrieved March 29, 2013.
o ^ Knox, Malcolm (June 11, 2008). “The game’s
up: jurors playing Sudoku abort trial”. The Sydney Morning Herald. Retrieved June 11, 2008.
o ^ Eisenhauer, William (2010). Sudoku-zilla. CreateSpace. p. 220. ISBN 978-1-4515-1049-2.
o ^ “What is Hyper Sudoku?”. sudoku-space.com. Retrieved August
o ^ *Snyder, Thomas; Huang, Wei-Hwa (2009). Mutant Sudoku. Puzzlewright Press. ISBN 978-1-402765025.
o ^ Conceptis, Puzzles (2013). Amazing Sudoku Variants. Puzzlewright. ISBN 978-1454906520.
o ^ Murali, A V (2014). A Collection of
Fascinating Games and Puzzles. CreateSpace Independent Publishing Platform. ISBN 978-1500216429.
o ^ Jump up to:a b “Zahlenraetsel”. janko.at.
o ^ Berthier, Denis (2007). The Hidden Logic of Sudoku. LULU PR. p. 76 N. ISBN 978-1-84753-472-9. p.
76.: “any block-free resolution rule is already valid in the theory of Latin Squares extended to candidates”. Restated more explicitly in the second edition, p. 86, as: “a block-free formula is valid for Sudoku if and only if it is valid for Latin
o ^ “NP complete – Sudoku” (PDF). Imai.is.su-tokyo.ac.jp. Archived from the original (PDF) on March 3, 2020. Retrieved October 20, 2013.
o ^ Lewis, R. A Guide to Graph Colouring: Algorithms and Applications. Springer International Publishers,
o ^ G. McGuire, B. Tugemann, G. Civario. “There is no 16-Clue Sudoku: Solving the Sudoku Minimum Number of Clues Problem”. Arxiv.org.
o ^ H.H. Lin, I-C. Wu. “No 16-clue puzzles exist. BOINC was used to solve it after 2 years and 8 months
or so.”, September, 2013.
o ^ Royle, Gordon. “Minimum Sudoku”. Archived from the original on November 26, 2006. Retrieved February 28, 2012.
o ^ プログラミングパズルに関心のある人は雑談しましょう. プログラミングパズル雑談コーナー [Programming Puzzle Idle Talk Corner] (in Japanese). Archived
from the original on October 12, 2016. Retrieved September 16, 2006.
o ^ Jarvis, Frazer (July 31, 2006). “Sudoku enumeration problems”. Frazer Jarvis’s home page. Retrieved September 16, 2006. Detailed calculation of this figure.
o ^ Jarvis,
Frazer; Russell, Ed (September 7, 2005). “There are 5472730538 essentially different Sudoku grids … and the Sudoku symmetry group”. Frazer Jarvis’s home page. Retrieved September 16, 2006.
o ^ Berthier, Denis (December 4, 2009). “Unbiased Statistics
of a CSP – A Controlled-Bias Generator”. In Elleithy, Khaled (ed.). Innovations in Computing Sciences and Software Engineering. pp. 165–70. Bibcode:2010iics.book…..S. Retrieved December 4, 2009.
o ^ “Sudoku title for Czech accountant”. BBC News.
March 11, 2006. Retrieved September 11, 2006.
o ^ “World Sudoku Championship 2006 Instructions Booklet” (PDF). BBC News. Retrieved May 24, 2010.
o ^ “Report on the 8th General Assembly of the World Puzzle Federation”. World Puzzle Federation.
October 30, 2006. Archived from the original on September 26, 2007. Retrieved November 15, 2006.
o ^ “Thomas Snyder wins World Sudoku Championship”. US Puzzle Team. March 31, 2007. Retrieved April 18, 2008.
o ^ Harvey, Michael (April 17, 2008).
“It’s a puzzle but sun, sea and beer can’t compete with Sudoku for British team”. TimesOnline. London. Retrieved April 18, 2008.
o ^ Malvern, Jack (April 27, 2009). “Su Doku battle goes a little off the wall”. TimesOnline. London. Retrieved April
o ^ “Pole, 23, repeats as Sudoku world champ”. PhillyInquirer. May 2, 2009. Archived from the original on May 5, 2010. Retrieved August 3, 2013.
o ^ “WSPC 2017 – Logic Masters India”. wspc2017.logicmastersindia.com.
o ^ “World Sudoku
Championships | WPF”. orldpuzzle.org.
o ^ “Thomas Snyder, World Sudoku champion”. The Philadelphia Inquirer. October 21, 2007. Retrieved October 21, 2007.
o ^ Shapiro, Howard (October 25, 2009). “Going for 2d, she wins 1st”. The Philadelphia Inquirer.
Archived from the original on November 2, 2009. Retrieved August 3, 2013.
o ^ Timpane, John (October 27, 2009). “Possible cheating probed at Sudoku National Championship”. The Philadelphia Inquirer. Archived from the original on November 1, 2009.
Retrieved August 3, 2013.
o ^ “3rd-place winner disqualified in Sudoku scandal”. The Philadelphia Inquirer. November 24, 2009. Archived from the original on November 27, 2009. Retrieved August 3, 2013.
Photo credit: https://www.flickr.com/photos/calliope/1484598527/’]