The History of Calcudoku
A young puzzle with old roots: arithmetic cages laid over a Latin square, first devised as a classroom exercise.
From a Classroom in Japan
This kind of puzzle is usually credited to Tetsuya Miyamoto, a Japanese mathematics teacher, who devised it around 2004 to train his pupils in calculation and logical thinking without telling them how to solve it. The idea soon spread beyond his classroom through puzzle books and newspapers.
Underneath the arithmetic lies the Latin square - a grid in which every symbol appears exactly once in each row and column - which mathematicians such as Leonhard Euler studied in the 18th century and which also sits at the heart of Sudoku.
Many Names, One Puzzle
The same kind of puzzle is also published commercially under the name KenKen. KenKen is a registered trademark of Nextoy LLC. PaperGames is not affiliated with Nextoy LLC and uses the generic name Calcudoku instead.
Every Calcudoku here is created fresh on your device: a random Latin square is cut into cages, each cage gets an operation that yields a whole number, and a built-in solver keeps only cuts that leave exactly one solution.