A Practical Guide to Solving Sudoku

Sudoku is a logic-based number placement puzzle. Fill the 9×9 grid so every row, column, and 3×3 box contains the digits 1 through 9 without repetition. Every Stealthdoku puzzle is checked for a unique solution and logical solvability.

Fundamental Techniques

• Naked Single: When only one candidate can fit a cell after checking its row, column, and box, place that number.
• Hidden Single: When a digit can fit in only one cell within a row, column, or box, it belongs there even when that cell has several candidates.
• Scanning and Cross-Hatching: Follow one number across nearby boxes, rows, and columns to eliminate conflicting positions.

Difficulty Levels

• Easy: Generous initial clues for casual solving or a quick mental reset.
• Normal: Balanced puzzles that reward careful scanning and single-candidate deduction.
• Hard: May require intermediate strategies, such as candidate interactions or pair formations.
• Expert: Designed for seasoned solvers using thorough elimination and disciplined deduction.

A Focused Break

A short logic puzzle offers a quiet pause from constant multitasking. Work through the grid at your own pace, return later if needed, or print an Easy and Normal puzzle for paper solving.