Solve Sudoku puzzles at various difficulty levels. Supports notes, hints, and undo.
Choose from Easy (35 given), Medium (30), Hard (25), or Expert (22). Numbers refer to pre-filled cells.
Click an empty cell and use the number pad or keyboard (1-9) to enter a number. Conflicts in the same row/column/box are highlighted in red.
Toggle notes mode to pencil in candidate numbers. When stuck, use the hint button (max 3 times) to reveal the correct answer.
Fill all cells correctly to see a congratulation message. Check your time with the timer.
Sudoku is a puzzle where you fill a 9x9 grid with numbers 1-9. Each row, column, and 3x3 box must contain each number exactly once. Use the pre-filled numbers as clues to fill in the remaining empty cells.
Start with obvious cells (where only one number is possible). Use the notes feature to track candidates. If a number can only go in one place within a row/column/box, fill it in. Learn techniques like Naked Pairs and Hidden Singles for harder puzzles.
Click the "Notes" button to activate notes mode, then enter numbers to show small candidates in cells. Enter the same number again to remove it. Turn off notes mode to return to normal input.
You can use up to 3 hints per game. Clicking the hint button fills the selected cell with the correct answer. If no cell is selected, a random empty cell receives the hint.
Sudoku is a logic-based number puzzle popularized in Japan in 1986 and is one of the most popular brain training games worldwide. It effectively improves concentration, logical thinking, and pattern recognition skills, with difficulty levels ranging from beginner to expert.
The origins of Sudoku can be traced to 18th-century Swiss mathematician Leonhard Euler's "Latin squares." The modern form first appeared in the US in 1979 and was popularized in Japan by Nikoli puzzle magazine under the name "Sudoku." Research shows that regular Sudoku solving helps improve memory, maintain cognitive abilities, reduce stress, and enhance mathematical thinking skills in students.
Effective Sudoku solving involves several techniques. "Naked Single" is used when only one candidate remains in a cell. "Hidden Single" is when a number can only go in one place within a row/column/box. Advanced techniques include "Naked Pairs/Triples," "X-Wing," and "Swordfish." Learning these strategies progressively enables you to solve expert-level puzzles.