Strategy Guide

Sudoku Strategies — From Beginner Tips to Advanced Techniques

By LK Forge  ·  7 min read

Sudoku looks intimidating, but every puzzle is solvable with pure logic — no guessing required. The goal is simple: fill the 9×9 grid so each row, column, and 3×3 box contains the digits 1 to 9 exactly once. The skill is knowing where to look. This guide walks from the two fundamentals every beginner needs through to the advanced techniques that crack the hardest grids.

Sudoku Tips for Beginners

New to Sudoku? Start with these two fundamental strategies — together they'll solve most easy puzzles and many medium ones right away.

Scan for Last Digits

Look at any row, column, or 3×3 box that is almost complete. If eight of the nine numbers are already filled in, the missing digit is your answer. This is the simplest technique in Sudoku and a great place to start every puzzle — clear the obvious cells first and the grid opens up.

Find Hidden Singles

When a number can go in only one cell within a row, column, or 3×3 box, that's a hidden single. Scan each group and ask: "Where can this number go?" If there's only one possible cell, fill it in — even if that cell still looks like it could hold other digits.

💡 Tip: Work digit by digit. Pick a number, then sweep every box asking where it can legally go. Hidden singles fall out fast, and the AI Hint button will name them for you while you learn the pattern.

Use Pencil Marks

Once the easy cells are gone, write small candidate numbers in each empty cell to track which values are still possible. Pencil marks are the foundation of every advanced technique and the key to solving harder puzzles systematically. In AI Sudoku you can add them by hand in Candidate mode, or switch on Auto Candidate Mode to have every cell's possibilities filled in automatically.

Advanced Sudoku Techniques

Once you're comfortable with the basics and you're tracking candidates, these strategies will help you tackle hard and evil puzzles.

Naked Pairs

If two cells in the same row, column, or box have exactly the same two candidates — say {4, 7} — then those two digits must occupy those two cells, in some order. That means you can safely erase 4 and 7 from every other cell in that group. Naked pairs (and their cousins, naked triples) often unlock a cascade of new singles.

Pointing Pairs

When a candidate digit inside a 3×3 box is confined to a single row or column of that box, the digit must land somewhere on that line within the box. So you can eliminate it from the rest of that row or column outside the box. The AI Hint engine uses naked pairs and pointing pairs to clear candidates before searching for the next move.

X-Wing

When a number can only appear in the same two columns across two different rows, you have an X-Wing. The four cells form a rectangle, and the digit must occupy two opposite corners. That lets you remove the candidate from those two columns everywhere else. It's one of the first "pattern" techniques, and a satisfying one to spot.

💡 Hard-mode tip: When you're stuck, stop scanning cells and scan digits across the whole grid. Patterns like X-Wings only become visible once your pencil marks are complete and accurate.

Quick Reference

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