The name of the puzzle comes from Japan. It consists of two Japanese characters: SU for number and DOKU for single. Originally the game had the long name "Suuji wa dokushin ni kagiru", which meant that the numbers had to meet only once, but they soon decided to shorten it to "Su Doku".
Curiously enough, the birthplace of the puzzle is not Japan, but Switzerland. The prototype of Sudoku was invented by the Swiss mathematician Leonhard Euler, who lived in the 18th century. He called his invention "Latin squares" or "Greco-Roman squares".
The playing field had four rows and four columns. Instead of numbers, letters of Greek and Latin alphabets were used. The first four letters of the Greek alphabet were combined with the first letters of the Latin alphabet. Each of the characters was not to be repeated in either row or column.
It wasn't until two centuries later that the game was modernized by the American architect Howard Garnes. He divided the grid into nine three-by-three blocks, each of which was now to contain a number rather than a letter. These changes made the puzzle much more complicated. Garnes called such a game "Number Place." It first appeared in 1979 in the American magazine Dell Puzzle Magazine. At the time, however, readers didn't notice the new puzzle game.
In 1984, a Japanese publication published "Sudoku," and the new game instantly gained incredible popularity. Separate compilations of the puzzle began to be released. In 2004, the game first appeared in an English newspaper, and since then the puzzle has spread around the world. The playing field is a square divided into nine small squares measuring three by three. Each square must be filled with numbers from 1 to 9, so that neither in a row, nor in a column, nor in a separate square numbers repeated. Players have hints beforehand - some cells are already filled with numbers. The more of them - the easier the level.