How to play Sudoku? Sudoku rules that you need to follow

How to play Sudoku and Sudoku Rules

Sudoku is played on a grid of 9×9 spaces. To play Sudoku, you need to fill up each row, column, and 3×3 square space within the 9×9 grid, with numbers from 1 to 9, without repetition. Easy right? Well, it depends. The game’s difficulty level is measured based on the count of numbers already placed at specific positions on the grid. In this article, you will learn about how to play Sudoku and get familiar with its rules that can help you solve the puzzle! 

Fundamental rules to play Sudoku

Sudoku is a logic-based game that can be designed in numerous different combinations. The game is played on a grid of 9×9 spaces. Playing Sudoku helps in increasing your thinking, problem-solving, and cognitive abilities. It is a puzzle based on patience, efficiency, and logic.

As many of you might misunderstand, Sudoku is not entirely based on mathematics. To play Sudoku, you need to be aware of the numbers from 1 to 9 and have the capability to think logically and efficiently. As you progress in the game, you need to consider some fundamental rules that inflict restrictions and make it difficult to solve the puzzle.

Here are 4 Key Sudoku rules that you need to keep in mind while solving the puzzle:

  • Rule 1 – You can use only numbers from 1 to 9 to fill the grid.
  • Rule-2: None of the numbers can repeat.
  • Rule-3: The sum of each row and column should be 45.
  • Rule-4: Use the process of elimination.

Rule-1: You can use only numbers from 1 to 9 to fill the grid

Sudoku is commonly played on a 9×9 grid, where each row, column, and 3×3 sub-grid needs to be filled with numbers ranging from 1 to 9. Each row, column, and box sub-section consists of 9 square boxes where numbers are entered.

Rule-2: None of the numbers can repeat

A simple rule governs the game: While filling up the boxes with numbers, you need to ensure that none of the numbers you place in any particular box repeats in any other part of the row, column, or 3×3 sub-grid.

Rule-3: The sum of each row and column should be 45

To figure out if you have missed any numbers, repeated a number, or placed a number in the wrong position, you can sum up all the numbers of the particular row, column, or the relevant 3×3 sub-grid to check if it adds to 45. If not, you might have missed, misplaced, or inserted a wrong number.

Rule-4: Use the process of elimination

You can find out which number should go in each of the empty spaces by using the process of elimination. This process helps you secure the numbers to be included in each square by checking which numbers are already present in the grid. For example, while checking which number is correct for a given space, you can determine it by eliminating the other numbers by checking for their existence in the other row/column/3×3 sub-grid it is common to.

How to play Sudoku?

The goal of Sudoku is pretty straightforward – fill in the numbers 1-9 without repetition in every row, column, and 3×3 grid. The best way to solve Sudoku is to use the method of elimination and deductive reasoning, which will allow you to figure out the rest of the numbers in the 9×9 grid. Check out the best Sudoku books that can improve your skills.

Here are 6 steps in which you can learn how to play Sudoku:

  • Step 1 – Get to know the Sudoku grid
  • Step 2 – Know the Sudoku rules
  • Step 3 – Start the game
  • Step 4 – Decode the numbers within each square
  • Step 5 – Mark all possible outcomes
  • Step 6 – Repeat until solved

Let’s look at each step in detail.

Step 1: Get to know the Sudoku Grid

Every Sudoku puzzle has a 9×9 grid of square boxes subdivided into a 3×3 sub-grid. Hence, there are a total of 81 squares on a Sudoku grid. Here is an example of the same:

How to play Sudoku - Step 1 - Get Familiar with the Grid

Step 2: Know the Sudoku rules

Sudoku rules are easy to understand and to solve the puzzle, there is only one fundamental rule that you need to be aware of. Each row, column, and 3×3 square space should have numbers 1-9, without repetition!

Step 3: Start the Game

Once you are aware of the rules of Sudoku, it’s time to start the game. When starting a new game of Sudoku, you will notice some of the square boxes are already filled with numbers. Now, the difficulty level depends on how many numbers are already filled in the grid; the lesser the number, the more difficult the game is. You must analyze the grid to fill in the empty spaces with specific numbers that do not repeat in the same column and row.

Tip: Start with the row, column, or 3×3 grid, where maximum numbers are already placed. 

Here is an example:

For the given Sudoku grid, you can easily fill up the square (horizontal line marked in red) in the image below with the process of elimination. Try it out, and then swipe left for the answer!

How to play sudoku - an example
Sudoku example

Step 4: Decode the numbers within each square

Once you start filling in the squares, the picture becomes clearer, and the positions of other numbers in the grid become more obvious. Now, you can fill the empty squares of the grid that are left. But you must understand that not every number you fill will help you uncover a new cell. So, you have to be conscious of this.

Step 5: Mark all possible outcomes

It is advisable for you to use a pencil to mark out all the possible numbers for a certain cell based on the information after thoroughly scanning the grid. To lock a particular number for a space might pose to be a little difficult for beginners. Therefore, instead of focusing on every empty box, it is much easier for you to only concentrate on one particular cell at a time.

Step 6: Repeat until solved

You need to repeat the above steps until all the empty spaces are filled, and voila, you’ve completed the game!

Sudoku puzzle solution

Sudoku, the number puzzle game, is an easy but challenging game. In fact, playing Sudoku has numerous benefits, as explained below:

  • Sudoku puzzles need you to focus on a single thing, and thus it helps to increase concentration.
  • It reduces anxiety and strain. Solving puzzles may help you overcome mental health problems like depression and anxiety disorder.
  • It strengthens your mental power.
  • Sudoku improves logical reasoning skills as you need to analyze possible numbers that can be filled in a particular square, demanding the employment of sharp deductive reasoning.
  • Sudoku enhances your memory skills and also sharpens your brain in the later stages of your life.
  • Playing Sudoku is a great way to have fun by challenging yourself mentally. It will improve not only your cognition but also your problem-solving skills. You can also learn patience and discipline through the game.

How to play Sudoku – FAQs

Do Sudoku puzzles have a diagonal Rule?

No. In general, the Sudoku puzzle game has no rules that say that the two nine-cell diagonals should consist of the numbers one to nine, each repeating only once.

How can sudoku be solved with pencil marking?

One of the most common and popular techniques to solve Sudoku puzzles is by using pencil marks. In complex Sudoku puzzles, it is helpful and necessary to use pencil marks for a hit and trial method. For example, if you’re certain that a particular box can be filled by one of only two numbers, you can use a pencil to add one of the numbers and see if it works out. If it doesn’t, you can simply erase it and replace it with the only other remaining number option to complete the row/column/3×3 grid accordingly.

How many combinations are possible in the Sudoku puzzle?

There are 6,670,903,752,021,072,936,960 unique possible combinations of numbers in a 9×9 Sudoku grid.

Is it necessary to know addition and subtraction to play Sudoku?

You need to know basic mathematical rules such as addition and subtraction to solve Sudoku puzzles. You should also possess the qualities of logical thinking and analytical and deduction skills for successfully solving the Sudoku puzzles.

Do the rules in Sudoku vary across difficulty levels?

There are mainly four difficulty levels, i.e., Easy, Medium, Hard, and Evil. But the rules and logic remain the same.

Is Sudoku good for your Brain?

Yes. Playing Sudoku helps boost concentration, improves memory and recall, and nurtures a healthy mindset. Take a look at the 14 benefits of playing sudoku here.