Japan's 'father of Sudoku' Maki Kaji dead at 69

Sudoku requires a player to put the numbers one to nine in a box made up of 81 squares, so that no number is repeated in any of the nine vertical or horizontal lines.

Japan's 'father of Sudoku' Maki Kaji dead at 69
Sudoku requires a player to put the numbers one to nine in a box made up of 81 squares, so that no number is repeated in any of the nine vertical or horizontal lines.