The history of Sudoku: from Latin squares to a global craze

Sudoku looks like it has been around forever, but the puzzle as we know it is only a few decades old. Its history crosses from 18th-century mathematics to an American puzzle magazine, a Japanese publisher, and finally a British newspaper that turned it into a worldwide craze.

Latin squares

The mathematical idea behind Sudoku is the Latin square: a grid where each symbol appears exactly once in every row and every column. The Swiss mathematician Leonhard Euler studied Latin squares in the 18th century. Sudoku adds one more constraint, the requirement that each 3×3 box also contains every digit, which turns a mathematical object into a puzzle.

Earlier number-placement puzzles appeared in French newspapers in the late 1800s, some quite close to modern Sudoku, but they faded away and didn't lead directly to today's game.

Number Place

The modern puzzle first appeared in 1979 in Dell Pencil Puzzles and Word Games, an American puzzle magazine, under the name "Number Place". It's generally credited to Howard Garns, an architect and puzzle constructor from Indiana. It was one puzzle among many in the magazine and attracted little attention at the time.

Japan names it Sudoku

In 1984, the Japanese puzzle publisher Nikoli introduced the puzzle in Japan. Its name was a shortened form of a longer Japanese phrase meaning roughly "the digits must remain single", which became "Sudoku". Nikoli also popularized an important design principle: puzzles should have a single solution, reachable by logic alone, and ideally be crafted with a pleasing, symmetrical pattern of starting numbers.

Sudoku became popular in Japan through the late 1980s and 1990s, while remaining largely unknown elsewhere.

The global craze

The breakthrough came through Wayne Gould, a retired judge from New Zealand who discovered Sudoku in Japan and spent years writing a computer program to generate puzzles. He persuaded The Times in London to publish them, and the first appeared in late 2004. Within months, most British newspapers were running daily Sudoku, and the craze spread quickly to newspapers, books, and electronic games around the world.

Why it caught on

Sudoku's appeal is partly its accessibility. It needs no language skills, no general knowledge, and no arithmetic, only logic. The rules take seconds to learn, yet puzzles range from gentle to extremely difficult. And a good Sudoku gives the satisfying sense that every step was earned by reasoning rather than luck.

How many Sudoku puzzles are there?

A lot. In 2005, mathematicians Bertram Felgenhauer and Frazer Jarvis calculated that there are about 6.67 × 10^21 valid completed Sudoku grids. Accounting for symmetries such as relabeling digits or rotating the grid, there are still about 5.5 billion essentially different grids. In 2012, researchers proved by exhaustive computer search that a Sudoku needs at least 17 starting clues to have a unique solution.

Today's puzzle

The daily Sudoku here offers easy, medium, and hard puzzles, each generated with a solver that confirms there's exactly one solution, in keeping with Nikoli's principle. If you want to improve, the Sudoku solving techniques guide explains the logic step by step.