The History of Sudoku
A Japanese name for an American puzzle, built on an idea from an 18th-century Swiss mathematician.
Before Sudoku: Latin squares and French newspapers
The idea behind Sudoku — a grid where each symbol appears once in every row and column — is a Latin square, studied by the Swiss mathematician Leonhard Euler in the 18th century. Sudoku adds a third constraint, the 3×3 boxes.
French newspapers of the 1890s, including Le Siècle and La France, printed number puzzles based on magic squares that came close to the modern form, but they used arithmetic and had different rules. They disappeared around the First World War.
1979: Number Place
The modern puzzle first appeared in 1979 in Dell Magazines' Pencil Puzzles & Word Games under the name Number Place. It is generally attributed to Howard Garns, a retired architect and freelance puzzle constructor from Indiana, who died in 1989 before the puzzle became famous.
1984: Japan gives it a name
In 1984 the Japanese puzzle publisher Nikoli introduced Number Place to Japan as Sūji wa dokushin ni kagiru — roughly “the digits must be single”. The name was soon shortened to Sudoku (数独). Nikoli also popularised hand-made puzzles with symmetrical clue patterns, a tradition many puzzle makers still follow.
2004–2005: the global boom
Wayne Gould, a retired judge from New Zealand living in Hong Kong, discovered Sudoku in Japan and spent years writing a computer program to produce puzzles. He persuaded The Times in London to publish one; it appeared on 12 November 2004. Other British papers followed within weeks, and by 2005 Sudoku was a worldwide craze in newspapers, books and on phones.
The first World Sudoku Championship was held in Lucca, Italy, in 2006, and the championships have continued under the World Puzzle Federation since.
Sudoku by the numbers
- 6,670,903,752,021,072,936,960 — the number of possible completed 9×9 Sudoku grids, calculated by Bertram Felgenhauer and Frazer Jarvis in 2005.
- 5,472,730,538 — the number of essentially different grids once symmetries such as relabelling digits and swapping rows are taken into account (Ed Russell and Frazer Jarvis).
- 17 — the minimum number of clues a Sudoku with a unique solution can have, proven in 2012 by Gary McGuire, Bastian Tugemann and Gilles Civario after an exhaustive computer search.
- 81 cells, 27 units — nine rows, nine columns and nine boxes, each containing the digits 1 to 9 once.