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Proven strategies to help you fill in the grid faster than ever
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Have you ever wondered how sudoku masters fly through a puzzle so fast when it feels like it takes you forever? Deducing which numbers fit in the grid can take up a lot of time, but by using a few simple strategies, you can learn to finish sudoku puzzles even faster than before. Keep reading for all of the best tips to find the right numbers, and shave a few minutes off your solve time!

Solving Sudoku Quickly: Best Beginner Tips

  1. Look for rows, columns, and squares with one empty cell you can quickly fill in.
  2. Scan each 3x3 square across and top-to-bottom to find cells with one solution.
  3. Pencil in all possible numbers into a cell and erase them as you solve.
  4. Focus on one section at a time and try a new spot if you get stuck.
  5. Set a timer to give you motivation to solve faster.
1

Find rows, columns, or squares with 1 empty cell.

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  1. This is one of the easiest ways to start a sudoku puzzle. Scan each row one by one from left to right, then each column from top to bottom. Look for rows, columns, and 3 x 3 squares where every number is filled in but one; that way, you can see what’s missing and fill in the cell easily.[1]
    • Scanning the rows and columns also helps familiarize yourself with the entire puzzle quickly.
    • Generally, if you’re not sure where to start working on a sudoku puzzle, it’s best to start on areas with the most given numbers.
    • Even if you don’t see any with only one empty cell, there will still be rows, columns, and squares with more filled-in numbers than others—so that’s where it’s easiest to begin.
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2

Scan each square from both directions.

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  1. Start by picking a square and scanning in one direction (horizontally across the grid). Look at the 3 x 3 squares next to the one you picked and see which numbers are already in each row. When you’re comfortable with that, scan in two directions (across the grid and up and down) to check the numbers in each row and column.[2]
    • For example, say you’re looking at a 3 x 3 square that’s missing the number 2. If you scan the adjacent squares and see that each has a 2, you can eliminate those rows in the first square you looked at (since neither can fit another 2).
    • Then, if you scan the sudoku vertically, you might see the square below also has a 2—which means that column also can’t be the one with a 2 in the square you picked.
3

Look for “single candidate” cells.

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  1. Sometimes, looking at the row, column, and square associated with a single cell can show you the number that belongs there, even if it’s not obvious at first glance. See if you can find an empty cell with only one solution because the other eight possible numbers appear in the row, column, and 3 x 3 square connected to that cell.[3]
    • For example, say you want to find the number for the center cell of a 3 x 3 square with a 1, 4, 5, and 8 in it.
    • Right away, you know 1, 4, 5, and 8 can’t go in that center cell because they’re already in the square.
    • Then, you might look at the center cell’s row and see a 2 and a 7 in the next square over.
    • Finally, the squares above and below in the same column might have a 3 and a 9 in them, meaning 6 is the only possible number that could fit in the center cell.
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4

Mark the possible numbers in each square.

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  1. Check which numbers are already present for each empty cell in the same row, square, and column. Since numbers can only appear once per row, column, and 3 x 3 square, you can eliminate any already used. Then, write down any leftover numbers that could still fit into the cell with a pencil.[4]
    • Try going through the entire puzzle and using the process of elimination to fill in each empty cell.
    • For example, if a row contains 2 and 3, a column contains 8, and a square contains 4 and 7, then write 1, 5, 6, and 9 into the cell since they’re the only possible numbers.
5

Find new cells that contain 1 possible number.

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  1. After you pencil in all the potential numbers, scan through the puzzle again for any cells with only a single number written in them, also known as “naked singles.” Since nothing else can fit into the cell, you can fill that number in and know it’s correct.[5]
    • Check the row, column, and square for the cells you just filled in and erase any other times the number you just wrote appears. That may help you find more single cells you can fill in.
    • You may also find “hidden singles” in the puzzle. If you notice a number only appears once in the row, column, or square regardless of the other numbers in the cell, then you know that that digit has to go there.
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7

Find naked pairs throughout the puzzle.

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8

Identify hidden pairs and hidden triples.

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  1. Similarly, hidden triples occur when three cells in a row, column, or square can only fit the same three numbers. Find hidden pairs and triples by making notes with your pencil so you can tell when you’ve narrowed down the possible numbers in each cell to the same options.[8]
    • For example, say one cell in a square has 3, 5, 7, and 9, and another cell in the same square has 3, 7, and 8. If 3 and 7 don’t appear anywhere else in the square, they must appear in those two cells.
    • Once you find hidden pairs and triples, you can use the scanning techniques above to find the right number for each cell.
9

Try the X-Wing method to eliminate numbers.

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  1. This scenario involves two cells with the same possible number in each of two rows, with those cells also in the same two columns. If there are no other cells in which the number could be a potential candidate, you can eliminate any other possible numbers in all four cells (which form an X when connected from corner to corner).[9]
    • For example, if the 4 empty cells could all contain a 5, then the 5 would have to appear in the top corner of one column and the bottom corner of another. You can erase every other 5 in the same rows and columns.
    • This technique is all about rows and columns, so try not to focus on the 3 x 3 squares in a sudoku puzzle when using it.
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10

Solve numbers on parallel lines with the Swordfish technique.

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  1. To use the Swordfish technique, look for a potential number in two cells in the same row. Look for two more rows that have two empty cells with the same potential number. Draw straight lines between the cells that are in a straight line with each other. If the lines form a closed loop making any shape, then you’ll recognize how to place the numbers so they don’t intersect.[10]
    • Since the number can never share the same row or column, you limit the possible locations you can place them.
11

Focus on one section at a time.

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12

Move to a new section when you get stuck.

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  1. If you can’t figure out what the numbers should be in the section you’re working on, don’t be afraid to leave it for now and hop somewhere else on the sudoku puzzle. You may be able to put in new numbers based on past deductions, and it could help you figure out the right numbers in the section you were stuck on.[12]
    • Don’t be afraid to step away and take a break altogether, either. Sudoku should be fun and relaxing—so if you start getting frustrated, it might be time for a break.
    • Clearing your mind with a short break may also help you catch things you missed earlier! Go grab a drink or snack, take a quick walk, or even just step away to take some deep breaths.
14

Start with easier puzzles.

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  1. Easier puzzles tend to have more given numbers and don’t require as many tricks to solve. Look for puzzles that are labeled “easy” or “beginner” if you’re just starting out with sudoku. When you want to test your skills even more, try a “medium” or “challenging” puzzle that takes more advanced solving techniques.[14]
    • “Hard” or “extreme” puzzles are the toughest and give you the least numbers in the grid, so you’ll have to use logic a lot more to fill in the cells.
15

Set a timer while you solve.

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  1. You can give yourself as much time as you want, but aim for somewhere between 5–15 minutes. After you set your timer, work on your sudoku puzzle without any distractions. If you easily finish within the time frame, then you can try setting even less time for your next puzzle.[15]
    • Having a timer can help you start fast (rather than hesitating to write in each number) and maintain your focus as you work!
    • If the timer goes off before you’re able to finish, try giving yourself a few extra minutes next time.
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About This Article

Joseph Meyer
Reviewed by:
Math Teacher
This article was reviewed by Joseph Meyer and by wikiHow staff writer, Glenn Carreau. Joseph Meyer is a High School Math Teacher based in Pittsburgh, Pennsylvania. He is an educator at City Charter High School, where he has been teaching for over 7 years. Joseph is also the founder of Sandbox Math, an online learning community dedicated to helping students succeed in Algebra. His site is set apart by its focus on fostering genuine comprehension through step-by-step understanding (instead of just getting the correct final answer), enabling learners to identify and overcome misunderstandings and confidently take on any test they face. He received his MA in Physics from Case Western Reserve University and his BA in Physics from Baldwin Wallace University. This article has been viewed 75,906 times.
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Co-authors: 6
Updated: December 2, 2024
Views: 75,906
Categories: Mathematical Puzzles
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