Kenkena

Kenkena is a mathematical puzzle game that combines elements of Sudoku and arithmetic. The game is played on a grid of square cells, typically 4x4, 5x5, or 6x6. Each cell must be filled with a digit from 1 to the size of the grid (e.g., 1-4 for a 4x4 grid).

The grid is divided into interlocking regions, known as "cages". Each cage is marked with a target number and a mathematical operator (addition, subtraction, multiplication, or division). The digits within a cage must combine using the specified operator to produce the target number. Importantly, the same digit can appear multiple times within a cage, as long as the cage's mathematical constraint is met.

Unlike Sudoku, Kenkena does not require that digits within rows or columns be unique. The primary rules are that all cells must be filled with valid digits and that the digits within each cage must satisfy the given arithmetic condition. The puzzle is solved by logical deduction and the application of arithmetic. Kenkena puzzles are often presented with increasing difficulty levels, determined by the grid size, the complexity of the cages, and the required mathematical operations. The game was invented by Tetsuya Miyamoto and first published in Japan in 2004.