How To Play Sudoku

Sudoku is an addictive game that is incredibly fun to play! It is a logic-based number-placement puzzle designed to be completed by a single person. Most people find sudoku to be mentally stimulating and quite challenging.

Although sudoku looks like a strange and complex puzzle when you first see it, the rules are very simple. You don’t need to be good at mathematics to play sudoku, you just need to be logical and determined. The best part is — the mental skills you learn from playing sudoku will help to improve your memory and deductive reasoning skills. It’s one of the few games that makes you smarter as you have fun!

This guide will explain how to play to sudoku and share some useful tips for solving your first sudoku puzzle.

How to play Sudoku

Sudoku will take you about five minutes to learn but quite a while to master. Let’s start by taking a look at the Sudoku square. It consists of nine boxes, with each box having nine squares inside of it. Take a look at the Sudoku puzzle below. The boxes are colored grey or white to help you tell them apart.

The objective of sudoku is simple — fill each box, row, and column with the numbers 1 to 9. Seems pretty simple right? Before you start randomly filling in numbers, you need to learn two important Sudoku rules:

Rule 1: Each number can only appear once in each box
Take a look at the highlighted box in the Sudoku puzzle below. The numbers 5, 6, 9, and 2 are already filled in. That means you cannot enter any of those numbers in that box again. You must find the correct space for 1, 3, 4, 7, an 8.

Rule 2: Each number can only appear once per column or row
This is where things start to get interesting! Looking at the example below, this rule means that the number 2 cannot appear again on the row or column that is highlighted.

These two simple rules are all you need to remember to play Sudoku. We’ll jump in and start solving this puzzle so you can see Sudoku in action. We’ll start with the middle box because it is almost complete.

Immediately, we can see that the two empty spots must contain either 4 or 5 — because the other numbers are already present in that square (Remembering rule 1: Each number can only appear once in each box).

But which number goes in which box? One way to solve this question is by looking outside of the box we are attempting to solve. If you look to the box on the left, you will notice that the number 4 is already present. Because it is on the middle row, it means another 4 cannot be placed on that row (rule 2: Each number can only appear once per column or line). This tells us that the 4 must belong in the upper left hand corner of the middle box, as shown below🙂

Now, there is only one spot left in the box and one number remaining — 5. So you can fill that in as well:

Congratulations, that box is now complete! You can now proceed to complete the rest of the puzzle.

Useful Sudoku tips

Sudoku puzzles aren’t always as easy as the demonstration above, so here are few tips to help you deal with more difficult puzzles:

1) Use a pencil when solving Sudoku puzzles
If you are completing a Sudoku puzzle that is on paper, use a pencil. That way, you can rub out any mistakes you make with an eraser. It also allows you to put a small reminder of the numbers that “could be” correct for a square.

For example, in the puzzle below, we know that the two empty squares on the middle right box can only be 4. That’s because there are already 4’s in the other rows and columns surrounding it (highlighted in red). However, we aren’t sure which box holds the 4 just yet. Place a little number 4 in each square, so you are reminded that a 4 will fit into either box.

2) Look for squares that are almost completed
When tackling a new Sudoku puzzle, start with squares that already have a lot of numbers in them. You can look for the numbers that are missing to narrow down what should be used. Easy Sudoku puzzles might give you 6 or 7 pre-filled numbers in a square, which makes it simple to get off to a good start.

3) Look for rows and columns that are almost completed
Some rows and columns may also have a lot of numbers pre-filled. Look along each row and column for missing numbers. In our example below, we can see that the highlighted row is nearly completed.

The highlighted row is missing the numbers 1, 2, and 9. Are there any obvious numbers that can be slotted in? Take a closer look at the 9. Where could it go? There is already a 9 in the left box and the middle box, so they are ruled out. It must go in the right box — and there is only one possible spot on that line.

4) Look at rows and columns with repeated numbers
Next, we’ll look at each row and column for numbers that are repeated. For example, in the puzzle below, the top row has 4s in the left and right box. That’s handy, because those 4s knock out a row each — meaning the 4 for the top middle box must be in the bottom row (either the bottom right or left position).

We then scan the columns to see if there is another 4. There is one in the middle box, which knocks out a column, meaning the 4 must go in the right. Once you learn to read Sudoku puzzles this way, the game will be much easier!

5) Scan across multiple squares
The game usually gets harder after you have placed in a few “easy” numbers. Now, you will have to scan across multiple columns to find a potential match. Choose a number and check if you can place it in all three squares, either vertically or horizontally. In many cases, you will have to pencil in a possibility with a small number, before confirming it later on.

6) Think about possibilities
When the going gets really tough or you are working on an advanced puzzle, you will have to think about “what if” scenarios. You will have to imagine what effect placing a 7 in a square might have on the other numbers, tracing that effect up multiple columns and rows. Really tough puzzles require you to visualize the consequences of placing a number much more. It becomes quite challenging!

Useful Resources