Sudoku is a well-known number-based logic puzzle that has captured the hearts of millions of players worldwide. Despite having simple rules, it requires focus, strategic thinking, and patience. In this guide, we’ll explain the rules of Sudoku in detail and show you how to play it correctly, even if you’re just beginning to explore this fun and engaging game.
Sudoku is a popular number puzzle that was invented in Japan. It consists of a 9×9 grid divided into smaller 3×3 blocks. Some cells are already filled with numbers from 1 to 9 (these are called “clues”), while the rest are empty. The goal of Sudoku is to fill all the empty cells with digits from 1 to 9 so that each row, each column, and each 3×3 block contains every digit only once. In other words, no number should repeat within any row, column, or block.
Sudoku doesn’t require any math — just logic, attention, and patience. It may seem tricky at first, but the rules are easy and always stay the same. The puzzle develops analytical thinking and is a great brain exercise. For many people, it becomes an enjoyable hobby.
Game board: A standard Sudoku puzzle has 81 cells (9 rows × 9 columns). Every 9 cells form a 3×3 square. At the beginning, some of the cells contain given numbers, called clues.
Filling rules: The player must fill the empty cells with numbers from 1 to 9, following three key rules (no other symbols allowed):
In other words, the same number cannot appear more than once in any row, column, or 3×3 square. For example, if the number 7 is already in the first row, you cannot place another 7 in that same row.
What’s not allowed: There are a few things that are not allowed in Sudoku:
How the game works: The player fills the empty cells step by step. After placing a number, make sure it doesn’t break the rules in its row, column, or block. If a rule is broken, it’s a mistake and the number shouldn’t be placed. A good Sudoku puzzle doesn’t need trial and error – the solution must be found logically at every step.
Take it step by step. Below is a general strategy for solving Sudoku, especially helpful for beginners:
Let’s look at a simple example to show how Sudoku is solved. Suppose we have a partially filled grid—a classic Sudoku with some clues already in place:
This is a standard Sudoku puzzle with clues. The task is to fill in the empty cells with digits 1–9 following the rules.
In the top-left 3×3 block, 7 out of 9 cells are filled. The missing numbers are 5 and 6. They must go in the remaining two spots, but it’s unclear where each belongs. It's best to leave this block and check elsewhere.
Now look at the leftmost column. It has three empty cells. The missing numbers are 1, 5, and 6. The number 1 is already in the top and middle blocks, so the only place left is the bottom-left block. Place the 1 using logical deduction.
Now return to the top-left block. Only 5 and 6 remain. With 1 placed, it becomes clearer: one cell can only take 5, and the other must be 6. Step by step, the whole puzzle gets solved.
Note: In a real Sudoku game, you often reason through several areas at once. Each move simplifies the puzzle, and the number of empty cells decreases until the board is full. When you fill the final cell, you’ve completed the puzzle!
New players should learn a few basic strategies to solve Sudoku. These help you find correct digits without guessing:
1. Single candidate in a cell: only one number fits in that spot.
2. Single position for a number: in a row, column, or block, a number can go in only one cell.
Beginners should always look for these obvious singles—they're the easiest way to make progress.
Experts say Sudoku is a game of logic, not guessing. Use step-by-step strategies and even difficult puzzles will become manageable.
Here are some common Sudoku mistakes and tips to avoid them:
Remember, mistakes are part of learning. Review what went wrong and try again. That’s how you improve your skills.
Now that you know the rules, strategies, and techniques, it’s time to practice. Start with an easy level, follow the advice, and build your skills. With each puzzle you solve, you’ll improve.
Try solving a Sudoku puzzle on our website now and see how enjoyable it can be!