36 Fun Facts About Sudoku

Which kind of reasoning does solving a Sudoku rely on?

Logic is all it takes: the digits are only labels, so any nine different symbols would make the same puzzle.

Under what name did Sudoku first appear in Dell Magazines in 1979?

Number Place was the name at Dell in New York, so the puzzle famous under a Japanese name actually began in an American magazine.

Which retired Indiana architect most likely designed the modern Sudoku?

Howard Garns died in 1989, years before his puzzle became a worldwide craze under a Japanese name.

How was the anonymous creator of Dell's 1979 grid puzzle identified?

His name only appeared in issues with it, a pattern a New York Times crossword editor spotted by checking back issues.

Which YouTube channel, run by two British puzzle experts, became a lockdown hit by solving Sudokus live on camera?

Cracking the Cryptic took off after co-host Simon Anthony quit his investment banking job to solve puzzles on YouTube.

Which British newspaper parodied the 2005 Sudoku craze by printing a grid on every page of a supplement?

The Guardian put a Sudoku on every page of its G2 section, cover included, while joking that its puzzles were hand-crafted by masters.

What does the Japanese word Sudoku literally mean?

Digit-single is the literal sense, because the puzzle's longer original name, 'the numbers must be single', was cut down to Sudoku.

Which publisher and company president is known as "the father of Sudoku"?

Maki Kaji dropped out of university before founding the puzzle magazine that gave Sudoku its name.

Which Stanford computer scientist gave 'dancing links', a classic technique for solving Sudoku by computer, its name?

Donald Knuth named the technique, but he credited the underlying trick to a 1979 paper by Hitotumatu and Noshita.

What two innovations did the puzzle's Japanese publisher introduce in 1986?

Symmetrical means the givens sit in rotationally symmetric cells, a convention most setters still follow.

What was the profession of Wayne Gould, who spread Sudoku outside Japan?

Hong Kong judge Wayne Gould found a Sudoku book in a Tokyo bookshop in 1997 and spent six years writing a program to generate puzzles.

Which was the first newspaper outside Japan to print a Sudoku, in September 2004?

The Conway Daily Sun, a small New Hampshire free paper, beat The Times of London to Gould's puzzles by two months.

What did Gould ask newspapers for in exchange for free puzzles?

A credit and a link to his site were enough, because Gould planned to make his money selling puzzle software.

Which Sudoku-style arithmetic puzzle did a Japanese maths teacher invent in 2004 to sharpen his students' thinking?

KenKen was designed to be solved without instructions, so students would learn through trial and error and independent thinking.

What was the BBC's 2005 game show combining Sudoku with general knowledge called?

It used only 4×4 and 6×6 grids and lasted four seasons.

Why was an Australian drugs trial costing over A$1 million aborted in 2008?

Four or five of the twelve jurors had been filling in grids instead of listening to the evidence.

Roughly how many completed 9×9 Sudoku solution grids exist?

Once rotations, reflections and relabellings are discounted, only 5,472,730,538 are essentially different.

A completed Sudoku grid is a special case of which mathematical object?

A Latin square only needs unique rows and columns; Sudoku adds the box constraint.

Euler's 'thirty-six officers' puzzle wanted no row or column to repeat an officer's rank or what?

Regiment: no arrangement of the 36 officers is possible, yet Euler's wider guess that other sizes like it were impossible too proved wrong.

Solving Sudoku on general n²×n² grids belongs to which complexity class?

Brute-force backtracking and dancing links still solve ordinary 9×9 puzzles quickly.

A Sudoku can be expressed as what kind of problem on a network of nodes and edges?

The aim is to complete a 9-colouring of a particular graph from a partial one.

Which country's newspapers printed Sudoku-like number grids in the 1890s, decades before Dell's version?

France: an 1895 puzzle in the daily La France came closest to modern Sudoku, yet it never marked the 3×3 boxes.

What name does the Japanese term Gattai 5 describe?

English-language papers such as The Times call the same layout Samurai Sudoku.

Which two puzzles does the Killer variant combine?

Sudoku and Kakuro combine in a grid that often starts with no digits at all, so solvers work from each cage's sum instead.

In Killer Sudoku, which rule lets solvers pin down lone 'innie' and 'outie' cells?

The Rule of 45 works because the digits 1 to 9 always total 45, so a lone cell is 45 minus the other cages in its row, column or box.

Which Sudoku solving technique shares its name with a Star Wars spacecraft?

X-Wing lets solvers clear a digit from the rest of two columns once two rows confine that digit to those same columns.

What is a 3-fish pattern called in Sudoku jargon?

A swordfish lets solvers clear a digit from the rest of three columns once three rows confine it to those columns.

What does a Sudoku solver mean by a "proper" puzzle?

A puzzle that needs no trial and error is called "satisfactory" instead.

Which 2020 YouTube Sudoku had its solver saying it was 'like the universe is singing to us'?

The Miracle Sudoku gave the solver just two digits to start from, yet its extra rules let him fill in the whole grid.

Which common variant requires the two main diagonals to contain unique digits too?

The Daily Mail's Sudoku X puzzles use 6×6 grids.

Which organisation has run the Sudoku global championship since 2006?

The first event was held in Lucca, Italy; it skipped 2020 and 2021 for the pandemic.

As of 2025, who has won the most individual World Sudoku Championship titles?

Kota Morinishi finished runner-up three years running before winning four titles between 2014 and 2018.

Which country's Jana Tylová won the individual title at the first World Sudoku Championship in 2006?

Czech Republic: Jana Tylová out-raced the tournament favourites, Americans Thomas Snyder and Wei-Hwa Huang, to take the first crown.

Where was the first World Sudoku Championship held in 2006?

Lucca, Italy staged the first championship, where the eventual winner had been as far back as eighth place heading into the final day.

Which company released the Sudoku-Bench reasoning benchmark in 2025?

Sakana AI found that even leading AI models could solve only a small share of Sudoku-Bench's puzzles.

Wayne Gould, who got newspapers around the world printing Sudoku, is originally from which country?

New Zealand: Gould may have spread the puzzle worldwide, but he says his wife, Gaye, solves Sudokus faster than he does.