Please use logical thinking instead of guessing! Each puzzle only has one solution.

In pen mode, you can directly import the candidate number by using Shift + number (Alt + number).
In pencil mode, you can directly import numbers by using Shift + number (Alt + number).
Key C (or Del, BackSpace): to deselect the number of the lattice or the candidate number.
Key ESC: to deselect.
Key P: a toggle switch to change from pencil and pen mode.

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.

Sudoku is consisted of 9x9 grids. For beginners, you can try mini Sudoku first. Or you can print them out and let kids solve them on printed paper by using pencils.