Beginner's Guide to Sudoku Rules – Learn How to Play Step-by-Step

New to Sudoku? This guide explains the goal, the rules you must follow, and a simple routine to solve beginner-level grids—without guessing. By the end, you'll know how to start, what to look for, and how to keep making progress.

What Sudoku Is (in 30 seconds)

• The board is a 9×9 grid split into nine 3×3 boxes.
• Fill empty cells with digits 1–9.
• Every row, column, and box must contain 1–9 once each—no repeats.

Think of the starting numbers as signposts. Your job is to place the remaining digits by logic.

The Four Rules You Must Follow

1. Use digits 1–9 only.
2. No repeats in any row, column, or 3×3 box.
3. Rely on deduction, not guessing.
4. One correct solution. If you hit a contradiction, backtrack and fix earlier steps.

How to Begin a Puzzle

1) Start with the obvious

Look for rows, columns, or boxes that are nearly complete. If a unit is missing one digit, place it immediately.

2) Hunt for "singles"

• Naked single: a cell has only one possible digit.
• Hidden single: inside a row/column/box, a digit can go in only one cell.

3) Use cross-checking / cross-hatching

Cross-check intersecting rows/columns to narrow where a digit can go inside a 3×3 box. Many players also call this pattern cross-hatching.

4) Add pencil marks

Write small candidate digits in empty cells. After each placement, remove candidates that no longer fit.

Mini Example

Suppose the middle column is missing 3, 5, and 8. Use rows/boxes to eliminate options. If only one cell can still be 8, place it—new singles often appear afterward.

Handy Beginner Techniques

• Block–line interactions: If a digit in a box can only sit on one row of that box, remove that digit from the rest of that row outside the box (and vice versa).
• Pairs & Triples (intro): Two cells share the same two candidates → those digits belong there; remove them elsewhere in the unit. Triples work similarly.
• Stay organized: Keep pencil marks tidy and update them after each placement.

Common Mistakes to Avoid

• Guessing early. It often causes dead ends and hidden errors.
• Ignoring boxes. Many beginner breakthroughs happen inside the 3×3 boxes.
• Not re-checking units. Every new placement can create fresh singles elsewhere.

Difficulty & Progress

Easier puzzles have more givens and are typically solved with singles. As you improve, explore pointing/claiming, pairs/triples, and grid-scanning patterns such as cross-hatching.

Ready to Practice?

Try this loop: scan → singles → cross-checking → pencil marks → repeat.

Beginner FAQ