Home › Guides › Sudoku Rules

solver

The Basics

Sudoku is a logic-based number puzzle that has become one of the world's most popular brain games. Despite using numbers, no math is required—only logical deduction and pattern recognition.

The goal is simple: fill a 9×9 grid with digits 1-9 following three basic rules. Each puzzle has a unique solution that can be reached through logic alone—never guessing.

💡 Key Fact

The name "Sudoku" comes from Japanese, meaning "single numbers" (数独, sūdoku). However, the modern puzzle was actually invented by an American architect, Howard Garns, in 1979.

The Three Rules

Every Sudoku puzzle follows exactly three rules:

1

Each Row Contains 1-9

Every horizontal row must contain each digit from 1 to 9 exactly once. No repetition allowed.

2

Each Column Contains 1-9

Every vertical column must contain each digit from 1 to 9 exactly once. No repetition allowed.

3

Each 3×3 Box Contains 1-9

Each of the nine 3×3 sub-grids (boxes) must contain each digit from 1 to 9 exactly once.

✅ Pro Tip

Think of it this way: every row, column, and box is like a container that needs exactly one of each number 1-9. If a number already exists in that container, it can't appear again.

Understanding the Grid

A standard Sudoku grid consists of:

  • 81 cells arranged in a 9×9 grid
  • 9 rows running horizontally
  • 9 columns running vertically
  • 9 boxes (3×3 sub-grids) outlined by thicker lines
534678912 672195348 198342567 859761423 426853791 713924856 961537284 287419635 345286179

Blue numbers are given clues; gray numbers are solved by the player

How to Start Solving

Follow these steps when approaching a new puzzle:

  1. Scan the grid - Look for rows, columns, or boxes that have many given numbers
  2. Find obvious placements - If a row/column/box is missing only one number, fill it in
  3. Use elimination - For each empty cell, determine which numbers are possible
  4. Look for singles - Find cells where only one number can go
  5. Repeat - Keep scanning and eliminating until the puzzle is complete

Basic Techniques

1. Scanning (Crosshatching)

Look at each number (1-9) and scan where it can go in empty boxes. Use the existing numbers in rows and columns to eliminate possibilities.

2. Naked Singles

When a cell has only one possible candidate after eliminating all numbers that appear in its row, column, and box, that candidate must go there.

3. Hidden Singles

When a number can only go in one cell within a row, column, or box—even if that cell has other candidates—that number must go there.

Tips for Beginners

✅ Do's

• Start with easy puzzles and gradually increase difficulty
• Use pencil marks to note possible candidates
• Take breaks when stuck—fresh eyes help
• Double-check each number placement

⚠️ Don'ts

• Never guess—Sudoku is pure logic
• Don't place a number unless you're 100% sure
• Avoid the temptation to look at solutions
• Don't give up—every puzzle has a solution

Frequently Asked Questions

Do I need to be good at math?

No! Sudoku uses numbers as symbols, but requires no mathematical calculations. You could use letters, colors, or shapes instead.

Can a Sudoku puzzle have multiple solutions?

A properly constructed Sudoku puzzle has exactly one unique solution. If a puzzle has multiple solutions, it's considered flawed.

Is guessing ever necessary?

Never. Every valid Sudoku puzzle can be solved through pure logic. If you feel the need to guess, you may have missed a logical deduction.

sudoku m

solver Sudoku variants like Killer Sudoku, Jigsaw Sudoku, and Sudoku-X provide additional challenges for players looking for something different from the classic version.

solver Tips for Improving Your Sudoku Speed

sudoku denver post

solver There are several difficulty levels in Sudoku, ranging from easy for beginners to expert for seasoned players. Solving techniques include scanning, cross-hatching, and identifying candidate numbers. will sudoku make you smarter Sudoku competitions are held globally, where speed solvers compete to finish complex grids in the shortest time possible. free printable sudoku puzzles pdf There are several difficulty levels in Sudoku, ranging from easy for beginners to expert for seasoned players. Solving techniques include scanning, cross-hatching, and identifying candidate numbers. best android sudoku app Sudoku variants like Killer Sudoku, Jigsaw Sudoku, and Sudoku-X provide additional challenges for players looking for something different from the classic version. best android sudoku app There are several difficulty levels in Sudoku, ranging from easy for beginners to expert for seasoned players. Solving techniques include scanning, cross-hatching, and identifying candidate numbers.

solver History of the Sudoku Puzzle

xwing sudoku

solver Advanced Sudoku solving methods involve complex patterns like X-Wing, Swordfish, and XY-Wing. These techniques are often required for hard and expert level puzzles. crazy sudoku puzzles Sudoku variants like Killer Sudoku, Jigsaw Sudoku, and Sudoku-X provide additional challenges for players looking for something different from the classic version. crazy sudoku puzzles Sudoku competitions are held globally, where speed solvers compete to finish complex grids in the shortest time possible. sudoku word To solve a Sudoku puzzle, one must look for cells where only one number is possible, or rows/columns/blocks where a specific number has only one possible placement.

solver Advanced Sudoku Solving Techniques

sudoku for elderly

solver Sudoku competitions are held globally, where speed solvers compete to finish complex grids in the shortest time possible. answer key to sudoku puzzles Playing Sudoku daily has many cognitive benefits, including improving memory, concentration, and logical reasoning skills. It is a great way to keep the brain active and healthy.

solver The Benefits of Playing Sudoku Daily

logic wiz sudoku

solver Modern Sudoku was popularized by Nikoli in Japan in the 1980s. It has since become a global phenomenon, with daily puzzles appearing in newspapers and online platforms worldwide. sudoku template Modern Sudoku was popularized by Nikoli in Japan in the 1980s. It has since become a global phenomenon, with daily puzzles appearing in newspapers and online platforms worldwide.

solver Common Sudoku Mistakes and How to Avoid Them

date everything doug sudoku

solver The rules of Sudoku are simple but the depth of the game is immense. Every well-posed Sudoku puzzle has a unique solution that can be reached through logical deduction. apple news sudoku Playing Sudoku daily has many cognitive benefits, including improving memory, concentration, and logical reasoning skills. It is a great way to keep the brain active and healthy. sudoku in chinese Sudoku is a logic-based, combinatorial number-placement puzzle. The objective is to fill a 9x9 grid with digits so that each column, each row, and each of the nine 3x3 subgrids contain all of the digits from 1 to 9. sudoku book print Sudoku competitions are held globally, where speed solvers compete to finish complex grids in the shortest time possible. sudoku book print Advanced Sudoku solving methods involve complex patterns like X-Wing, Swordfish, and XY-Wing. These techniques are often required for hard and expert level puzzles.

solver What is Sudoku and How to Play?

hardest sudoku game ever

solver To solve a Sudoku puzzle, one must look for cells where only one number is possible, or rows/columns/blocks where a specific number has only one possible placement. complete the present tense tener sudoku puzzle Advanced Sudoku solving methods involve complex patterns like X-Wing, Swordfish, and XY-Wing. These techniques are often required for hard and expert level puzzles. what is the goal of sudoku Sudoku variants like Killer Sudoku, Jigsaw Sudoku, and Sudoku-X provide additional challenges for players looking for something different from the classic version. four by four sudoku Sudoku is a logic-based, combinatorial number-placement puzzle. The objective is to fill a 9x9 grid with digits so that each column, each row, and each of the nine 3x3 subgrids contain all of the digits from 1 to 9.

solver Tips for Improving Your Sudoku Speed

sudoku with balls

solver The rules of Sudoku are simple but the depth of the game is immense. Every well-posed Sudoku puzzle has a unique solution that can be reached through logical deduction. simple sudoku game There are several difficulty levels in Sudoku, ranging from easy for beginners to expert for seasoned players. Solving techniques include scanning, cross-hatching, and identifying candidate numbers. crazy sudoku Sudoku competitions are held globally, where speed solvers compete to finish complex grids in the shortest time possible. andrew sudoku solver Sudoku variants like Killer Sudoku, Jigsaw Sudoku, and Sudoku-X provide additional challenges for players looking for something different from the classic version. blank sudoku grid to print Playing Sudoku daily has many cognitive benefits, including improving memory, concentration, and logical reasoning skills. It is a great way to keep the brain active and healthy.

Related Topics

sudoku blank multiple sudoku printable how to solve hard sudoku puzzle sudoku techniques expert how to solve medium level sudoku making a sudoku puzzle

🔍 Related Searches

sudoku empty rectangle sudoku speed sudoku tips hard medium sudoku printouts intermediate sudoku Finding Last Cell Complex Logic Hard Sudoku Puzzles Intermediate Sudoku Expert Killer Sudoku Killer Sudoku Online Insane Killer Mode