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In 1986, Nikoli introduced two innovations: the number of givens was restricted to no more than 32, and puzzles became "symmetrical" (meaning the givens were distributed in rotationally symmetric cells). "Sudoku" is a registered trademark in Japan and the puzzle is generally referred to as Number Place ( ナンバープレース, Nanbāpurēsu) or, more informally, a shortening of the two words, Num(ber) Pla(ce) ( ナンプレ, Nanpure). The name was later abbreviated to Sudoku (数独), taking only the first kanji of compound words to form a shorter version. The puzzle was introduced in Japan by Maki Kaji ( 鍜治 真起, Kaji Maki ), president of the Nikoli puzzle company, in the paper Monthly Nikolist in April 1984 as Sūji wa dokushin ni kagiru ( 数字は独身に限る), which can be translated as "the digits must be single", or as "the digits are limited to one occurrence" (In Japanese, dokushin means an "unmarried person"). Whether or not Garns was familiar with any of the French newspapers listed above is unclear. He died in 1989 before getting a chance to see his creation as a worldwide phenomenon. Garns' 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. 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). These weekly puzzles were a feature of French newspapers such as L'Écho de Paris for about a decade, but disappeared about the time of World War I. 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.

It simplified the 9×9 magic square puzzle so that each row, column, and broken diagonals contained only the numbers 1–9, but did not mark the subsquares. On July 6, 1895, Le Siècle 's rival, La France, refined the puzzle so that it was almost a modern Sudoku and named it carré magique diabolique ('diabolical magic square'). 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. Le Siècle, a Paris daily, published a partially completed 9×9 magic square with 3×3 subsquares on November 19, 1892. Number puzzles appeared in newspapers in the late 19th century, when French puzzle setters began experimenting with removing numbers from magic squares. newspaper, and then The Times (London), in 2004, thanks to the efforts of Wayne Gould, who devised a computer program to rapidly produce unique puzzles.įrom La France newspaper, July 6, 1895: The puzzle instructions read, "Use the numbers 1 to 9 nine times each to complete the grid in such a way that the horizontal, vertical, and two main diagonal lines all add up to the same total." Predecessors 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 "single number". The puzzle setter provides a partially completed grid, which for a well-posed puzzle has a single solution.įrench 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. 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.

Sudoku ( / s uː ˈ d oʊ k uː, - ˈ d ɒ k-, s ə-/ Japanese: 数独, romanized: sūdoku, lit.'digit-single' originally called Number Place) is a logic-based, combinatorial number-placement puzzle.