Home › Guides › Sudoku Rules

washington post diagonal sudoku

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 puzzle printouts

washington post diagonal 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. electronic sudoku handheld game Many people enjoy solving Sudoku as a relaxing hobby. It provides a sense of accomplishment when a difficult puzzle is finally completed correctly.

washington post diagonal sudoku Different Types of Sudoku Variants

two player sudoku

washington post diagonal sudoku Sudoku competitions are held globally, where speed solvers compete to finish complex grids in the shortest time possible. medium sudoku nyt answers 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. medium sudoku nyt answers Sudoku variants like Killer Sudoku, Jigsaw Sudoku, and Sudoku-X provide additional challenges for players looking for something different from the classic version. sudoku 5x5 Sudoku variants like Killer Sudoku, Jigsaw Sudoku, and Sudoku-X provide additional challenges for players looking for something different from the classic version.

washington post diagonal sudoku What is Sudoku and How to Play?

portland press herald sudoku

washington post diagonal 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. dell 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 blank grid printable 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. killer sudoku daily 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. medium sudoku nyt 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.

washington post diagonal sudoku The Benefits of Playing Sudoku Daily

mini sudoku book

washington post diagonal 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. nyt daily 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. print samurai 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.

washington post diagonal sudoku How to Solve Hard Sudoku Puzzles Step by Step

best sudoku app reddit

washington post diagonal 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. amazon sudoku Sudoku variants like Killer Sudoku, Jigsaw Sudoku, and Sudoku-X provide additional challenges for players looking for something different from the classic version. artisanal sudoku Sudoku competitions are held globally, where speed solvers compete to finish complex grids in the shortest time possible. 16x16 sudoku online Sudoku competitions are held globally, where speed solvers compete to finish complex grids in the shortest time possible.

washington post diagonal sudoku Advanced Sudoku Solving Techniques

create a sudoku game

washington post diagonal sudoku Sudoku variants like Killer Sudoku, Jigsaw Sudoku, and Sudoku-X provide additional challenges for players looking for something different from the classic version. brainbashers killer 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. printable easy sudoku puzzles Many people enjoy solving Sudoku as a relaxing hobby. It provides a sense of accomplishment when a difficult puzzle is finally completed correctly. printable easy sudoku puzzles 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. crazy dad sudoku Sudoku variants like Killer Sudoku, Jigsaw Sudoku, and Sudoku-X provide additional challenges for players looking for something different from the classic version.

washington post diagonal sudoku Different Types of Sudoku Variants

sudoku photo

washington post diagonal sudoku 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. washpost sudoku Sudoku competitions are held globally, where speed solvers compete to finish complex grids in the shortest time possible. medium difficulty sudoku Sudoku variants like Killer Sudoku, Jigsaw Sudoku, and Sudoku-X provide additional challenges for players looking for something different from the classic version. medium difficulty sudoku Sudoku competitions are held globally, where speed solvers compete to finish complex grids in the shortest time possible.

Related Topics

jigsaw sudoku 9x9 sudoku post sudoku logical reasoning skills sudoku printouts sudoku word 4x4 sudoku

🔍 Related Searches

sudoku subscription how do you solve hard sudoku puzzles sudoku latimes jason linhart sudoku sudoku hard new york times Finding Numbers Naked Triples Rule Solving Strategies Unique Candidate Sum Sudoku Advanced Removal Evil Sudoku Mode