How to Play Sudoku: Rules and Beginner Steps
Sudoku is a logic puzzle played on a 9×9 grid. The goal is simple: fill every row, column, and 3×3 box with the digits 1 through 9, without repeating any number in a row, column, or box.
You do not need math. You only need careful observation and logical deduction.
The three Sudoku rules
Every valid Sudoku puzzle follows exactly three rules:
- Each row must contain the digits 1–9 exactly once.
- Each column must contain the digits 1–9 exactly once.
- Each 3×3 box must contain the digits 1–9 exactly once.
The grid starts with some numbers already filled in. These are called givens or clues. Your job is to deduce the rest.
How the grid is organized
A standard Sudoku board has:
- 9 rows (horizontal)
- 9 columns (vertical)
- 9 boxes (each box is a 3×3 region)
When you focus on one empty cell, always check all three constraints at once: its row, its column, and its box.
Your first steps as a beginner
1. Scan for obvious placements
Start by looking for cells where only one number can fit. If a row already contains 1, 2, 3, 4, 5, 6, 7, and 8, the empty cell in that row must be 9.
Do the same scan for columns and boxes. These easy placements build momentum.
2. Use pencil marks (candidates)
For harder cells, note which numbers are still possible. In Sudoku Guru, tap the notes button to write small candidate numbers in a cell.
Pencil marks help you see patterns and avoid guessing.
3. Work systematically
Many beginners jump around the grid randomly. Instead, pick a strategy:
- Scan all rows, then all columns, then all boxes.
- Or focus on one box at a time.
Consistency reduces mistakes.
4. Never guess early
A good Sudoku puzzle is designed to be solved by logic alone. If you feel stuck, you probably missed an elimination — re-scan with pencil marks rather than guessing.
Common beginner mistakes
- Forgetting the box rule — a number might be valid in a row and column but already appear in the same 3×3 box.
- Rushing — Sudoku rewards patience. One wrong digit can cascade into many errors.
- Skipping pencil marks — candidates make hidden patterns visible.
Frequently asked questions
Is Sudoku a math game?
No. Sudoku uses digits as symbols. You never add, subtract, or calculate — you only place numbers according to the three rules.
How many clues does a puzzle need?
Most published puzzles have 17 to 35 givens. Fewer clues usually mean a harder puzzle, but difficulty also depends on which solving techniques are required.
Can I play Sudoku on my phone?
Yes. Play free Sudoku on Sudoku Guru with multiple difficulty levels, hints, and offline-friendly classic mode.
Practice what you learned
The fastest way to improve is to solve puzzles regularly. Start on Easy, apply the three rules, and use pencil marks whenever you hesitate.