Sudoku Tips: How to Solve Sudoku for Beginners

New to Sudoku? Learn the fundamental techniques to solve any puzzle, from easy to hard difficulty.

Understanding the Rules

Sudoku is a 9×9 grid puzzle. The goal is simple: fill every empty cell with a digit from 1 to 9 so that:

• Each row contains 1-9 exactly once
• Each column contains 1-9 exactly once
• Each 3×3 box contains 1-9 exactly once

No math required — just logic and pattern recognition.

Technique 1: Scanning (Easiest)

Start by scanning rows and columns to find cells that can only have one possible number.

Example: If a row already has 1, 2, 3, 5, 6, 7, 8, 9 — the missing number is 4. Find where 4 goes in that row.

Do this for every row and column. You'll often find 5-10 cells this way right at the start.

Technique 2: Cross-Hatching

This is the most powerful beginner technique. Focus on one 3×3 box at a time.

Steps:

1. Pick a number (e.g., 5)
2. Look at the rows and columns that pass through a 3×3 box
3. Eliminate cells where 5 can't go because 5 already appears in that row/column
4. If only one cell remains in the box, that's where 5 goes

Repeat for every number 1-9 and every box. You'll be surprised how many cells you can fill this way.

Technique 3: Pencil Marks

When a cell has multiple possible candidates, write them down lightly (use the Hint button in our game for assistance).

Example: A cell might be able to contain 3, 5, or 7. Write all three as pencil marks. As you solve other cells, you'll eliminate options until only one remains.

Tip: Don't overdo pencil marks — only add them when you're down to 2-3 candidates per cell.

Technique 4: Naked Pairs

If two cells in the same row/column/box can only contain the same two numbers (e.g., both can only be 3 or 7), then no other cell in that group can be 3 or 7.

Example: If two cells in a row are both limited to {3, 7}, then 3 and 7 are "locked" in those two cells. Eliminate 3 and 7 from all other cells in that row.

Common Mistakes

• Guessing — Sudoku is pure logic. If you guess, you'll eventually get stuck or solve it wrong.
• Ignoring the 3×3 boxes — beginners focus only on rows/columns and forget the box constraint.
• Not using pencil marks — trying to hold all possibilities in your head leads to mistakes.
• Giving up too early — hard puzzles require patience. Take a break and come back with fresh eyes.

Difficulty Levels

• Easy (40 given): Uses scanning + cross-hatching. Good for beginners.
• Medium (30 given): Requires pencil marks and some naked pairs.
• Hard (25 given): Needs advanced techniques like hidden pairs, X-wings, and swordfish.

Ready to Practice?

Try these techniques in our free Sudoku game. It includes hints, error checking, and best time tracking.