CalcuDoku is a mathematical and logical puzzle loosely similar to sudoku. It was invented by a Japanese mathematics teacher Tetsuya Miyamoto. The objective is to fill the grid in with the digits 1 through N (where N is the number of rows or columns in the grid) such that: - Each row contains exactly one of each digit. - Each column contains exactly one of each digit. - Each bold-outlined group of cells (block) contains digits which achieve the specified result using the specified mathematical operation: addition (+), subtraction (-), multiplication (×), and division (÷). - Unlike Killer Sudoku, digits may repeat within a block. brain games for adults - brain teasers riddles - mind puzzle games - mind puzzles for adults - puzzle games for adults - brain busters - math brain teasers - brain teasers and answers - riddles and brain teasers - brain twister - mind teaser puzzles - mind games for adults - funny puzzles - mental puzzles