How to Play Sudoku & Solve Any Puzzle: Beginner & Advanced Tips

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Try these simple strategies to improve your sudoku skills
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Sudoku puzzles may seem intimidating at first, but with a bit of practice, they’re pretty easy to solve. These puzzles don’t actually involve math (thankfully). Instead, they’re all about pattern recognition. In this article, we’ll teach you everything you need to know to solve a sudoku puzzle, from learning the basic rules and setup to trying different techniques like scanning the puzzle for answers and filling in candidates. Plus, learn how to fix mistakes and get unstuck during tough puzzles.

Solving a Sudoku: Quick Tips

Start by identifying a single empty cell within a row, column, or block and filling in the missing number. Write down all potential answers to each square and fill in any cells that only have one candidate. Also look for numbers repeated twice within a row of 3 blocks—if you find the same number in two blocks, you know that same number goes somewhere in the third block of that row.

Section 1 of 5:

Sudoku Rules & Layout

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  1. A sudoku grid consists of a square grid of 9 large squares, often called blocks. Within each of those blocks will be 9 smaller squares. Some of those squares will be filled with numbers from 1 to 9. Easier puzzles will have more numbers filled in, while more difficult puzzles will have fewer squares filled. [1]
    • The larger squares are often outlined with a darker line, while the smaller squares have a thinner line. Additionally, sometimes the larger squares will be colored in a checkerboard pattern.
  2. Each row, column, and block should contain all of the numbers from 1 to 9. That means that within a row, column, or block, a number cannot repeat. Your job is to figure out where each number goes to complete the puzzle. [2]
    • For example, if a block (large square) already has the number “2” in it, you know it can’t include another “2” anywhere in the square.
    • Similarly, if a column already has a “3,” it can’t have another “3,” even if it’s in a different block.
    • It’s better to use a pencil rather than a pen when solving sudoku. This way, you can erase any mistakes you make and keep your board clean. Remember to write lightly so you can erase better.
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Section 2 of 5:

Using the Scanning Strategy

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  1. Examine each large block to see if it has a single square open. Or, run your finger down each row and column to see if they have one empty, as well. These single empty squares are called “naked singles.” They’re easy to fill in because you just have to figure out which number is missing from 1 to 9. [3]
    • For example, if a block has the numbers 1-3 and 5-9, you know it’s missing the number “4,” which you can fill in.
    • Or, if a column has numbers 1-7 and 9, you know it’s missing the number “8.”
    • This is one of the easiest strategies to use, especially when just starting the puzzle.
  2. Look at a row of 3 blocks and check for a number that’s repeated 2 times in different blocks. Run your fingers along the rows (or columns) that contain that number. The third block must contain the same number, but it can’t be in either of the rows you’re tracing; it must be in the third row. Sometimes, 2 other numbers will be in that row, so you can easily fill in the number you’re scanning. [4]
    • For example, if “8” is repeated in 2 blocks, look for that number in the third block. Run your finger down the rows with each “8,” as you know the “8” can’t be in either of those rows in the third block.
    • Once you get the hang of scanning across just rows or columns, add the other direction as well.
  3. That is, if you see that you have a lot of one number on the board, it can help to start trying to fill in the rest of that number. For example, say you have a large number of 5s on the board. Use your scanning techniques to fill in as many 5s as you can. This still requires you to examine blocks, rows, and columns to make sure they don’t repeat. [5]
    • Another option is to include 3 blocks in a row or column in your analysis. Pick 1 number, and see if you can place it across all 3 squares. For instance, take the number "6." See which rows and columns already have 6s, and use that to scan across to the 3 blocks you're looking at. Based on that information and what you have in the squares, try to place as many of the 6s as you can.
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Section 3 of 5:

Filling in Candidates

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  1. A candidate is any number that could belong in a certain square. Pencil in all possible entries for each square. Then, check to see if any squares contain only one possible answer. This is a “forced” entry that you can fill in. [6]
  2. A naked pair (sometimes called a conjugate pair) is a set of two candidates that could go in two different squares within a block, row, or column. Because you know these numbers must go in one of these squares, eliminate them as candidates in other squares in that block, column, or row. [7]
    • For example, let’s say you’ve marked all the candidates within a block and you notice the numbers “2” and “8” are the only two candidates that could go in two different squares. These are your naked pairs, so they cannot go in any other square within the block except the two you’ve marked.
  3. Hidden pairs are similar to naked pairs, in that they are two numbers that can only go in two cells within a block, row, or column. However, these cells also contain at least one other candidate, which is what makes them “hidden.” Carefully examine the candidates in each of your squares to find two that contain the same two numbers. [8]
    • For example, let’s say one cell within a block contains the candidates 1, 4, and 7. Another cell contains the numbers 1, 8, and 7. Because they both contain 1 and 7, this is your hidden pair. Eliminate the numbers 1 and 7 from all other cells within the block.
  4. An X-wing is an advanced technique used to remove candidates in difficult puzzles . First, look for a row that contains the same candidate in two different spots. Then, find a parallel row that mirrors it and contains the same candidates in the same spots. This allows you to remove those candidates from the columns that contain those cells. [9]
    • For example, let’s say the first row of the grid contains a 4 as a candidate in the 2nd and 5th squares. The third row of the grid also contains a 4 in the 2nd and 5th squares. This allows you to erase the 4 as a candidate in all other squares in the 2nd and 5th columns, because it must go in either the first or third row.
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Section 4 of 5:

Fixing Mistakes & Getting Unstuck

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  1. If you’ve narrowed a cell down to one or two candidates, you may be tempted to pick one at random. This may result in getting a few more “answers,” but at some point, you’ll likely realize the puzzle is now impossible to solve—often toward the end of the game. To avoid putting in a lot of hard work for nothing, make sure you’re confident about each choice you make. [10]
    • If you’re stumped by a certain cell, it’s okay to come back to it later. There may be an easier solution somewhere else in the puzzle.
    • Recheck the puzzle often. As you fill in numbers, you may be able to figure out the answers to spaces you had to leave blank before.
  2. It’s a good idea to do sudoku puzzles in pencil because, odds are, you’ll need to do some erasing at some point. If you realize you made a mistake, try to retrace the last few steps you made. Pay attention to each number to try to determine which one is incorrect. If you can’t find the mistake, it may be easier to start from scratch. [11]
  3. If you can’t figure out what to do next, set the puzzle down and take a break. Take some deep breaths or go for a short walk. If you’re frustrated, it will be harder to find the patterns you’re looking for, so return to the puzzle once your brain has had time to relax. You may be able to figure out some answers you couldn’t see earlier.
  4. Sudoku is a game of pattern recognition, which is a skill learned over time. It’s okay to make mistakes, especially if you’re just learning how to play. If you get stuck , don’t get discouraged. Keep trying different puzzles and different techniques until you get the hang of it. Even practicing as little as 5 minutes a day can help! [12]
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Section 5 of 5:

Does sudoku involve math?

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  1. While patterns are technically a part of math, solving a sudoku puzzle does not use math as we typically think of it (like adding and subtracting). The use of numbers can be intimidating, but they could actually be replaced with other symbols, like letters or shapes. The game would still be played the same way. [13]

Sample Sudoku Puzzles

Blank Sudoku Template

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    Are all sudoku puzzles solvable?
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    Yes, unless the puzzle was printed with an error, which is unlikely.
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    When all of the squares are the correct numbers, can I assume the rows and columns are correct?
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    The numbers in the 9 squares cannot be "correct," as you say, unless the rows and columns are also correct. You can have all 9 squares with all 9 numbers, but that does not guarantee that the rows and columns will be correct.
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    Is there an easy way to play sudoku?
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    Once you get the hang of it, it will become pretty easy and fun.
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      Tips

      • It may be easier to start with online sudoku puzzles! Many websites let you choose the difficulty level, so stick with “beginner” or “easy” puzzles until you get the hang of it. Then, challenge yourself with more difficult puzzles!
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      Warnings

      • For every cell you fill in, make sure you double-check your logic; a single error could mess up the entire puzzle.
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      References

      1. ↑ https://bestofsudoku.com/sudoku-strategy
      2. ↑ https://www.pennydellpuzzles.com/wp-content/uploads/2019/03/How-to-Solve-Sudoku.pdf?srsltid=AfmBOopj-nLmLZYYVU8hNxbOQGtkvd9Z5cdU8lP70ikr5KDcc_P9kJ_W
      3. ↑ https://www.stolaf.edu/people/hansonr/sudoku/explain.htm
      4. ↑ https://www.stolaf.edu/people/hansonr/sudoku/explain.htm
      5. ↑ https://bestofsudoku.com/sudoku-strategy
      6. ↑ https://www.pennydellpuzzles.com/wp-content/uploads/2019/03/How-to-Solve-Sudoku.pdf?srsltid=AfmBOopj-nLmLZYYVU8hNxbOQGtkvd9Z5cdU8lP70ikr5KDcc_P9kJ_W
      7. ↑ https://www.pennydellpuzzles.com/wp-content/uploads/2019/03/How-to-Solve-Sudoku.pdf?srsltid=AfmBOopj-nLmLZYYVU8hNxbOQGtkvd9Z5cdU8lP70ikr5KDcc_P9kJ_W
      8. ↑ https://www.pennydellpuzzles.com/wp-content/uploads/2019/03/How-to-Solve-Sudoku.pdf?srsltid=AfmBOopj-nLmLZYYVU8hNxbOQGtkvd9Z5cdU8lP70ikr5KDcc_P9kJ_W
      9. ↑ https://www.sudoku.org.uk/SolvingTechniques/X-WingFamily.asp
      1. ↑ https://bestofsudoku.com/sudoku-strategy
      2. ↑ https://bestofsudoku.com/sudoku-strategy
      3. ↑ https://sudoku.com/how-to-play/how-to-improve-your-sudoku-skills-in-5-minutes-or-less/
      4. ↑ https://bestofsudoku.com/sudoku-strategy

      About This Article

      Article Summary X

      Sudoku is a game played on a 9 x 9 grid where the object of the game is to fill every space with the correct number. The grid is divided into 9 separate 3 x 3 squares. To complete the grid, every column, row and square (each containing 9 spaces) needs to be filled in with the numbers 1-9 without repeating any numbers within the row, column or square. Some squares already have numbers filled in, so begin by look for missing numbers in a row, column or square. For example, if a square already has 7 out of the 9 spaces filled in, you can figure out which 2 numbers are missing and use the numbers in the correlating rows and columns to determine which of the two missing numbers belongs in each space. If you see a single empty space in a larger square, fill that in first. Then look for single empty squares in each row and column that you can fill in. Next, you can start scanning each row for a certain number, like 1, to see where it should go. Every Sudoku has one solution, so double check by making sure each column, row and square contains the numbers 1-9 with no duplicates or omissions. Continue using logic and deduction until you have filled in all of the empty squares. Once you have filled in all of the squares with the correct numbers, you win the game! To learn how to do more advanced sudoku techniques, like adding up the rows and columns, read on!

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        Jun 25, 2018

        "My husband was a Sudoku nut. I always secretly admired his attention to the game and his apparent success. It ..." more
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