Sudoku
Sudoku is one of the most popular calculation games. It is played by employing logical thinking. The calculation process does not require calculus or any special mathematics expertise. You only need to brainstorm and concentrate. If you play Sudoku every day, you can improve your concentrated force and further develop your brain potential.

Sudoku Rules
The process of solving Sudoku is filling numbers from 1-9 into 9x9 grids. Numbers in each column and each row (3x3 grids in rough-line boxes) cannot be repetitive.

Number 1-9 can only appear once in each column.
Number 1-9 can only appear once in each row.
Number 1-9 can only appear once in each group.