Sudoku Basics for Beginners

Introduction to Sudoku

Sudoku is a logic-based number placement puzzle. The objective is to fill a 9×9 grid with digits so that each column, each row, and each of the nine 3×3 subgrids (also called boxes or regions) contain all of the digits from 1 to 9.

The puzzle setter provides a partially completed grid, which typically has a unique solution. The difficulty of the puzzle depends on how many numbers are initially revealed and their positions.

Basic Rules

1. Each row must contain the numbers 1-9 without repetition
2. Each column must contain the numbers 1-9 without repetition
3. Each 3×3 box must contain the numbers 1-9 without repetition

Getting Started

When you first look at a Sudoku puzzle, it might seem overwhelming. Here's a simple approach to get started:

1. Scan the grid: Look for rows, columns, or boxes that already have several numbers filled in. These areas will give you the most immediate clues.
2. Look for "singles": Find cells where only one number can go based on what's already in the related row, column, and box.
3. Use elimination: For each empty cell, determine which numbers are already present in the related row, column, and box. The remaining numbers are candidates for that cell.

Basic Techniques

Scanning

Scanning involves looking at rows, columns, and boxes to identify where a specific number can be placed. For example, if you're looking to place the number 5, check where 5 already appears in the grid, then use those positions to eliminate possibilities in other rows, columns, and boxes.

Elimination

For each empty cell, identify which numbers are already present in its row, column, and box. The numbers that remain are the only possible candidates for that cell. If only one number remains, you can confidently place it.

Common Beginner Mistakes

• Guessing: Sudoku is a logic puzzle. You should never need to guess if the puzzle is properly constructed.
• Not using pencil marks: For harder puzzles, it's helpful to note possible numbers for each cell.
• Focusing too much on one area: Sometimes you need to look at the entire grid to find the next move.
• Missing obvious patterns: Take your time and be methodical. Sometimes the simplest patterns are the easiest to overlook.