Sudoku

Su-Doku is a logic-based number placement puzzle. Its objective is to insert the digits in such a way that each digit is unique in the region of 3x3 boxes and also in that particular row and column. Completed Su-Doku puzzles are a Type of Latin square, with an additional constraint on the contents of individual regions. Invented by an American in 1979 and published by Dell Magazines under the name ‘Number Place’, the modern puzzle became popular in Japan in 1986, when it was given the name Su-Doku. The word is abbreviated form of Japanese phrase ‘Suji wa dokushin ni kagiru’ meaning ‘the number must occur once’. These puzzles have become extremely popular the world-over in the past few years and are highly recommended by the experts in improving logical thinking.