How to Solve Sudoku: A Beginner Method Without Guessing

Look for a row, column, or box with only a few empty squares. Identify which digits are missing. Then check the crossing units for each empty square. A nearly full area gives you fewer possibilities to compare, so it is an easier starting point than a mostly blank area.

For example, suppose a row is missing only 2 and 7. If one empty square's column already contains 7, that square must be 2. The other empty square in the row must then be 7, provided the puzzle is valid. You did not need to try both orders: the column eliminated one.

A candidate is a digit that could legally go in an empty square based on the numbers currently visible in its row, column, and box. To find candidates, start with 1 through 9 and cross out any digit already used in those three areas. If only one remains, you have a certain move.

You do not need to write every possible digit across the whole board at once. Begin with one crowded row or box and record only the few cells you are examining. Our Sudoku game does not have a pencil-mark mode, so you can track candidates mentally or on paper while playing. Never enter a candidate in the grid as though it were confirmed.

This is sometimes called a naked single. One empty square has just one candidate left after you check its row, column, and box. If the row rules out 1, 2, 3, and 4, the column rules out 5, 6, and 7, and the box rules out 8, the only remaining digit is 9.

Before you enter that 9, double-check that you looked at the correct 3x3 box. A fast scan can accidentally use a number from the box beside it. Once the placement is certain, add it and revisit the affected row, column, and box: another cell may now have just one candidate.

A hidden single asks a different question. Instead of looking for a square with one possible digit, choose one missing digit in a row, column, or box and ask where it can go. If a 3x3 box still needs 6, but the crossing rows or columns block 6 from every empty square except one, that one square must be 6.

The square might still allow other digits when viewed alone. The 6 is certain because no other square in that box can hold it. Sweep the grid one digit at a time when cell-by-cell scanning stops producing moves. This is often simpler than trying to consider every empty square at once.

Every confirmed placement changes three areas: its row, its column, and its box. After writing a number, check those areas again before hunting elsewhere. Remove the placed digit from any candidate lists there and see whether a new single has appeared. A Sudoku solve is usually a chain of small deductions, not one clever leap.

If you are playing on Puzzle Game Hub, selecting a square highlights related squares, making its row, column, and box easier to inspect. The game also marks an incorrect entry. Use that feedback to recheck your deduction, rather than typing several uncertain numbers and waiting to see what turns red.

First, recheck the clues and your own entries. A mistaken digit can make a later square appear impossible. Then try the opposite scan: if you were looking at cells, follow one digit through a box; if you were following digits, calculate candidates for a crowded cell. Move to another part of the board if one area has no clear answer.

An Easy puzzle is a better training ground than a Hard one while you learn these moves. If you use our Hint button, it fills a correct empty square but does not show the reasoning. Before continuing, inspect the row, column, and box to understand why that number belongs there. Some harder grids require techniques beyond singles; being stuck is not a reason to guess blindly.

Open the Sudoku game above, choose Easy, and make one placement you can explain aloud: “This cell is 2 because its column already has 7,” or “This box's 6 has only one place.” Continue only with moves you can justify. That habit makes errors easier to spot and helps you learn more from each puzzle than racing to fill the grid.

When that feels comfortable, try Medium. Keep the same scan, candidate, single, and repeat routine; add more advanced patterns only when the puzzle actually calls for them.