Home › Guides › Sudoku Rules

sudoku boston globe

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 seattle

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

sudoku boston globe Advanced Sudoku Solving Techniques

jigsaw sudoku

sudoku boston globe 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 for 3rd graders 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.

sudoku boston globe Tips for Improving Your Sudoku Speed

sudoku com evil

sudoku boston globe 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. sudoku online printable free 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. new york times hard sudoku 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 boston globe Sudoku Strategies: Scanning and Marking

how to say sudoku

sudoku boston globe 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. janric sudoku 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.

sudoku boston globe History of the Sudoku Puzzle

sudoku methods

sudoku boston globe Sudoku competitions are held globally, where speed solvers compete to finish complex grids in the shortest time possible. samurai sudoku online 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.

sudoku boston globe Basic Sudoku Rules for Beginners

when does nyt sudoku reset

sudoku boston globe 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.cba.si answers 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.

sudoku boston globe Basic Sudoku Rules for Beginners

sudoku pronunciation

sudoku boston globe Sudoku variants like Killer Sudoku, Jigsaw Sudoku, and Sudoku-X provide additional challenges for players looking for something different from the classic version. jigsaw 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. x wing 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. evil sudoku extreme online 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. sudoku free printable medium 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

very hard sudoku printable best free sudoku app for ipad sudoku algorithms history of sudoku game directions on how to play sudoku sudoku new york post

🔍 Related Searches

is sudoku math hard killer sudoku sudoku target sudoku tutorial tricks for solving hard sudoku Pointing Triples Difficult Killer Sum Sudoku Advanced Sudoku Advanced Removal Elimination Technique Sudoku Y-Wing