For how long has the puzzle existed?
The recognised puzzle of Sudoku first arrived in a magazine called Nikoli in Japan in the late 1980s, having previously been published in the late 1970s by the New York puzzle magazine Math Problems and Logic Puzzles, published by Dell, under the title “Number Place”. It may have originated from a game called Latin Squares or Magic Squares thought up by the Swiss mathematician, Leonhard Euler. He invented Magic Squares or carrés magiques in 1783. Magic Squares had fewer restrictions than Sudoku with no lines dividing the square.
