What Is Sudoku?
Sudoku is a logic-based number placement puzzle played on a 9×9 grid. Despite using numbers 1 through 9, it requires no mathematics — only reasoning and pattern recognition. The goal is simple: fill every cell so that each row, column, and 3×3 box contains each digit exactly once.
Understanding the Grid
Before you solve your first puzzle, it helps to understand how the grid is structured:
- Rows: 9 horizontal lines, each must contain digits 1–9 with no repeats.
- Columns: 9 vertical lines, each must also contain digits 1–9 with no repeats.
- Boxes (Regions): Nine 3×3 sub-grids — each must contain digits 1–9 with no repeats.
Every cell belongs to exactly one row, one column, and one box. That overlap is the key to solving the puzzle.
The Three Core Rules
- Each row must contain the digits 1–9, no repetition.
- Each column must contain the digits 1–9, no repetition.
- Each 3×3 box must contain the digits 1–9, no repetition.
A valid Sudoku puzzle has exactly one solution that satisfies all three rules simultaneously.
How to Start Solving: The Scanning Method
The best technique for beginners is called scanning. Here's how it works:
Step 1 — Cross-Hatching
Pick a digit, say the number 5. Look at each row and column that already contains a 5. By eliminating the rows and columns those 5s occupy, you can often narrow down exactly where the next 5 must go in an empty box.
Step 2 — Lone Singles
Look for any cell where only one digit is possible. If a cell's row contains 1, 3, 4, 6, 7, 8, 9 and its column and box add 2 and 5 — then that cell must be the remaining digit.
Step 3 — Counting Within a Box
Within each 3×3 box, check which digits are missing. If eight of the nine digits are already placed, the final empty cell can only hold the one remaining number.
Beginner Tips to Keep in Mind
- Start with the boxes, rows, or columns that already have the most digits filled in — they're the easiest to complete.
- Use a pencil! Lightly write candidate numbers in corners of cells, then erase as you eliminate options.
- Never guess. If you're not sure, gather more information before placing a digit.
- Work on one digit at a time across the entire grid before moving to the next.
Choosing Your First Puzzle Difficulty
Sudoku puzzles are typically rated Easy, Medium, Hard, and Expert. As a beginner, always start with Easy puzzles. These are designed so that every step can be solved using simple scanning and lone-single techniques — no advanced logic required.
Ready to Begin?
Print out a free Easy Sudoku puzzle, grab a pencil, and apply the scanning and lone-single methods described above. Most beginners complete their first Easy puzzle within 20–30 minutes. With practice, you'll quickly build speed and confidence to tackle Medium and Hard puzzles.
Remember: every Sudoku grandmaster started exactly where you are. The key is consistency — solve one puzzle a day and you'll be amazed at how quickly your skills grow.