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Fill the Grid
Place digits 1–9 in every empty cell of the 9×9 board.
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No Repeats in Rows
Each horizontal row must contain 1–9 with no digit repeated.
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No Repeats in Columns
Each vertical column must also contain every digit 1–9 once.
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No Repeats in Boxes
Each of the nine 3×3 boxes must contain all nine digits exactly once.
How do you solve Sudoku step by step?
Start by scanning each row, column and box for any digit that can only go in one cell (naked singles). Then look for hidden singles — a digit that only fits in one place within a unit. Use pencil marks to track candidates and gradually eliminate them until the grid is complete.
Is guessing allowed in Sudoku?
Proper Sudoku puzzles are designed to be solved with pure logic — no guessing required. If you find yourself guessing, it usually means a logical step has been missed. This game highlights mistakes immediately so you can correct your reasoning.
How long does a Sudoku puzzle take?
An Easy puzzle typically takes 5–10 minutes. Medium puzzles average 15–25 minutes. Hard puzzles can take 30–60 minutes or more. The built-in timer lets you track and improve your personal best time.
Can I play Sudoku on mobile?
Yes. Sudoku NumGrid is fully mobile-responsive — tap any cell to select it and use the on-screen number pad. It works on iPhone, Android, and any tablet or desktop browser with no download required.