Brit + Co Guides Logo

How to play sudoku

Useful tips to solve every puzzle!

65
STEPS
TOOLS

To play sudoku, you have to fill each square, horizontal, and vertical line with the numbers 1-9. There are 9 squares. The easier puzzles have more numbers (and less blanks) to fill.

Sudoku isn't really a "mathematical" game. It has to do with logic, and the best method I've found so far to solve the puzzles is the process of elimination.

Start with 1. Find all the ones, and look to see if any "naked singles" show up. Naked singles are digits that obviously cannot go any place else. There are only two 1's here so no naked singles.

In the beginning stages of solving each puzzle I try to fill in the possibilities of where each digit can go. In the top center square 1 can only go two places.

In the beginning stages of solving each puzzle I try to fill in the possibilities of where each digit can go. In the top center square 1 can only go two places.

So I lightly pencil them in.

So I lightly pencil them in.

I only like to pencil in these possibilities if there are less than two of them. But this will increase as the game progresses to three or four.

In this puzzle 5 was the first naked single I found. Because in the center square it can't go anywhere else. The other 5's cancel out all other options.

After filling in all the possibilities, and naked singles, your puzzle will look more or less like this.

Except the 9's in the center square show me that I need to get rid of the 9 beneath them. So the 9 in the bottom right hand corner of the bottom center square is the only choice.

Except the 9's in the center square show me that I need to get rid of the 9 beneath them. So the 9 in the bottom right hand corner of the bottom center square is the only choice.

This shows me that there is only one place for 4 to go.

This shows me that there is only one place for 4 to go.

I can also reason that 9 would go in the two center slots in the right center square. I know this because the horizontal line needs a 9, and it can't go in the other squares.

I can also reason that 9 would go in the two center slots in the right center square. I know this because the horizontal line needs a 9, and it can't go in the other squares.

At this point, I look in each square starting with the one with the least amount of blanks. I count and see what numbers are left.

In the bottom left-hand square I see that 1, 2, 4, and 5 are left.

In the bottom left-hand square I see that 1, 2, 4, and 5 are left.

I pencil in all of these.

I pencil in all of these.

After repeating this process a few reasonable times, I look horizontally. Beginning with the horizontal line with the least blanks left, I work on the possibilities.

In the bottom left-hand square, we can reason that 4 must go in the bottom horizontal line because there's no other place for it in that line.

In the bottom left-hand square, we can reason that 4 must go in the bottom horizontal line because there's no other place for it in that line.

In the same square we also see that because 5 cannot go in the upper slots it has to go in the only space available... (circled).

In the same square we also see that because 5 cannot go in the upper slots it has to go in the only space available... (circled).

Continue these steps until you find every number! And don't forget to erase the incorrect possibilities when you've filled a blank. Good luck & remember these puzzles are for FUN!!

If you want to solve... Just print!

If you want to solve... Just print!

Finished result: ANSWER KEY

Last tips! Sometimes I circle a blank if I know the two possibilities are absolute. Also, you can use a pen to mark which numbers you're positive about, and use the pencil for guesses.

  • Pencil (for erasing!)
  • Sudoku puzzle
  • Your brain ;)