Sudoku for Beginners
Sudoku is one of the most popular logic puzzles in the world — and for good reason. It requires no math, no language skills, and no prior experience. All you need is patience and the ability to follow simple rules. This guide will take you from complete beginner to confident solver.
What Is Sudoku?
Sudoku is a number placement puzzle played on a 9×9 grid. The grid is divided into nine 3×3 sections called boxes (sometimes called regions or blocks). Some cells are pre-filled with digits — these are called clues or givens. Your job is to fill in the remaining empty cells.
The digits you use are 1 through 9. Every digit appears exactly nine times in a completed puzzle — once in each row, once in each column, and once in each box.
The Three Rules
Sudoku has exactly three rules. Learn these and you know how to play:
- Every row must contain the digits 1–9, each exactly once.
- Every column must contain the digits 1–9, each exactly once.
- Every 3×3 box must contain the digits 1–9, each exactly once.
That's it. No digit can repeat within any row, column, or box. Every valid solution satisfies all three rules simultaneously — and every properly constructed puzzle has exactly one solution.
Understanding the Grid
Before you solve, get comfortable reading the grid:
- Rows run left to right. There are 9 rows, numbered 1–9 from top to bottom.
- Columns run top to bottom. There are 9 columns, numbered 1–9 from left to right.
- Boxes are the nine 3×3 sections. Think of them as a 3×3 grid of boxes.
- Each cell belongs to exactly one row, one column, and one box.
When you place a digit in a cell, it affects all three groups that cell belongs to. A single placement can unlock many other cells — this chain reaction is what makes sudoku satisfying to solve.
Your First Technique: Last Remaining Cell
Start here. Look for any row, column, or box that has eight of its nine cells already filled in. The one empty cell can only hold the one missing digit.
For example: if a row contains 1, 2, 3, 4, 5, 6, 7, 9 — the empty cell must be 8. No calculation needed. This technique alone can solve a large portion of an easy puzzle.
Your Second Technique: Process of Elimination
When no group has only one empty cell, try this. Pick any empty cell and ask: which digits are already in its row? Its column? Its box? Any digit that already appears in any of those three groups cannot go in this cell.
If you eliminate eight of the nine digits, the one that remains is your answer. If more than one digit remains, move to a different cell and try again.
Your Third Technique: Digit Scanning
Pick a digit — say, 5 — and find all the 5s already on the board. For each 3×3 box that doesn't have a 5 yet, look at the empty cells inside it. Any cell that shares a row or column with an existing 5 is eliminated. If only one cell in the box remains, that's where the 5 goes.
This technique works best for digits that appear frequently — the more already placed, the easier it is to locate the remaining ones.
How to Approach Your First Puzzle
- Start with easy difficulty — it's designed for beginners.
- Scan every row, column, and box for the Last Remaining Cell pattern first.
- Apply elimination to any cells that still seem unclear.
- Scan for the digit that appears most on the board.
- Repeat. Each digit you place makes other cells easier.
- Never guess — every step in a well-made puzzle has a logical answer.
Common Beginner Questions
Do I need to use all digits from 1–9?
Yes. In a completed puzzle, every digit from 1 to 9 appears exactly nine times.
Can a cell be empty in the final solution?
No. Every cell must be filled with exactly one digit.
What if I get stuck?
Go back to basics. Check every row, column, and box systematically. On easy puzzles,
there is always a logical next step — you may have missed a constraint.
Is guessing allowed?
Technically, but it's not good practice. Good puzzles never require guessing.
If you feel stuck, use elimination more carefully rather than guessing.
Ready to Play?
The fastest way to learn is to play. Start with an easy puzzle and apply the three techniques from this guide.
Play a free Easy Sudoku puzzle →