Sudoku Solving Techniques for Beginners (9×9 and 6×6 Mini)

Sudoku's rule is simple: fill the grid so every row, column, and box contains each number exactly once. The Classic 9×9 grid uses digits 1-9 in nine 3x3 boxes; the Mini 6×6 grid uses digits 1-6 in six 2x3 boxes. The rule never changes, but a handful of techniques will take you from staring blankly at a grid to solving it confidently.

Technique 1: Scanning (Cross-Hatching)

Pick a number, say 7, and look at one box at a time. Scan across every row and down every column that already contains a 7 - those lines are eliminated for that box. If scanning leaves only one empty cell in the box where a 7 could legally go, that's your placement. Scanning is the fastest technique and solves the majority of an Easy puzzle by itself.

Technique 2: Single Candidate (Naked Single)

Look at a single empty cell and list every number that isn't already used in its row, column, and box. If only one number survives that filter, it must go in that cell - there's no other legal option. This is the most reliable technique because it never requires comparing multiple cells at once.

Technique 3: Pencil Marks

Once scanning stops finding easy placements, start writing small candidate numbers in the corner of each empty cell - every number that isn't yet ruled out for that cell. This turns the puzzle from a memory exercise into a visual one: patterns that were invisible before (like a candidate number appearing in only one cell of a box) suddenly stand out.

Technique 4: Hidden Single

A hidden single is the reverse of a naked single: instead of a cell having only one candidate, a number has only one possible cell within a box, row, or column - even though that cell also lists other candidates. Scan your pencil marks for a number that appears in only one cell of a box, and place it there, ignoring the cell's other candidates.

Technique 5: Pointing Pairs

If a candidate number appears in only two or three cells of a box, and those cells all sit in the same row or column, that number can be eliminated from every other cell in that row or column outside the box. This technique bridges box-level and line-level logic, and it's usually the key to unlocking Medium and Hard puzzles once scanning and singles stop making progress.

How This Differs Between 9×9 and 6×6

The Mini 6×6 grid uses the exact same techniques, just with a smaller candidate pool (1-6) and 2x3 boxes instead of 3x3 - which makes it a faster way to practice pencil marks and pointing pairs before tackling the full 9×9 grid.

Common Mistakes

• Guessing instead of eliminating - a well-formed Sudoku always has a unique solution reachable through logic, so a guess that doesn't pan out means you missed a deduction, not that the puzzle needed luck.
• Skipping pencil marks on Medium+ puzzles - trying to hold every candidate in your head works for Easy puzzles but breaks down fast once pointing pairs and hidden singles are required.
• Only scanning boxes and forgetting to scan rows/columns directly for hidden singles once the box-based scan stalls.

Start with the Mini 6×6 grid to build pattern recognition, then move to Classic 9×9 once pencil marks feel natural.