**Calcudoku** (*"KenKen"*, *"KENKEN"*, *"KenDoku"*, *"Mathdoku"*, *"Square Wisdom"*) 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.

At some puzzles the signs of mathematical operations may absent (all signs or part of them). This makes the solving process more complicated.

**Cross+A** can solve and create puzzles from **3 x 3** to **9 x 9**.