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.
There are 10 references
cited in this article, which can be found at the bottom of the page.
This article has been fact-checked, ensuring the accuracy of any cited facts and confirming the authority of its sources.
This article has been viewed 75,972 times.
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
- Look for rows, columns, and squares with one empty cell you can quickly fill in.
- Scan each 3x3 square across and top-to-bottom to find cells with one solution.
- Pencil in all possible numbers into a cell and erase them as you solve.
- Focus on one section at a time and try a new spot if you get stuck.
- Set a timer to give you motivation to solve faster.
Steps
-
If every other cell is filled, you only have one possible number to write in. 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] X Research source
- 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.
-
Use this technique to narrow down where each number can go. 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] X Research source
- 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.
-
Single candidates are cells that only have one possible solution. 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] X Research source
- 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.
-
Filling cells with potential numbers lets you see each possibility. 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] X Research source
- 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.
-
You may have uncovered a cell's solution after adding pencil marks. 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] X Research source
- 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.
-
Numbers appearing only in a single row or column in a square must go there. Focus on one 3 x 3 square at a time and scan through all the possible numbers you penciled in. If a number appears in a cell or multiple cells in a single row or column, it can’t appear in the same section of a different square. You may not know the exact spot for the number yet, but you eliminated where it could be elsewhere in the puzzle. [6] X Research source
-
Naked pairs are two cells with the same two potential numbers. Because each cell of a naked pair can only fit one of two numbers, you’ll know those numbers have to be in those positions—and you can erase any other instance where you penciled them in the same row. Go through the whole puzzle and check for naked pairs in each row, column, and 3 x 3 square. [7] X Research source
- For example, if 3 and 9 are the only options for two cells in the same column, then erase 3 and 9 pencil marks from the other cells.
-
Hidden pairs can only be in two cells in the same row, column, or square. 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] X Research source
- 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.
-
The X-Wing method is useful on the most challenging sudoku puzzles. 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] X Research source
- 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.
-
The Swordfish strategy gives possible placements in 3 rows and columns. 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] X Research source
- Since the number can never share the same row or column, you limit the possible locations you can place them.
-
Sticking with one row, column, or square feels less overwhelming. Rather than trying to work on the entire puzzle at the same time, look at the section of the puzzle that has the fewest empty cells. Try to work through and deduce as many numbers in that row, column, or square as you can. That way, you’ll have more information to work with when you work on the rest of the puzzle. [11] X Research source
- You can even work on an entire row or column of 3 x 3 squares at a time to help you see which values are missing.
-
Working on another part of the puzzle helps you get fresh eyes. 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] X Research source
- 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.
-
You’ll lose a lot of time if you have to go back and correct the puzzle. Sudoku puzzles only have one solution, and you can always deduce a number somewhere on the grid. Rather than making a guess when you don’t know a number, keep scanning the puzzle to recheck if potential numbers can still fit into the cells. You’ll find a cell you can fill or narrow down to certain numbers that way! [13] X Research source
-
Work your way up to difficult puzzles as you learn solving techniques. 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] X Research source
- “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.
-
You’ll feel more focused when you’re in a time crunch. 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] X Research source
- 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.
-
The more you practice, the faster you’ll be able to solve puzzles. If you’re a beginner, trying your hand at sudoku puzzles (while using the techniques above) is the best way to get better at solving them fast—and consistently. Over time, you’ll learn to recognize puzzle patterns and get comfortable using different techniques. Eventually, you’ll be a pro! [16] X Research source
Expert Q&A
Video
Tips
You Might Also Like
References
- ↑ https://www.stolaf.edu/people/hansonr/sudoku/explain.htm
- ↑ https://www.stolaf.edu/people/hansonr/sudoku/explain.htm
- ↑ https://www.stolaf.edu/people/hansonr/sudoku/explain.htm
- ↑ https://www.learn-sudoku.com/pencil-marks.html
- ↑ https://www.stolaf.edu/people/hansonr/sudoku/explain.htm
- ↑ http://hodoku.sourceforge.net/en/tech_intersections.php
- ↑ https://www.sudokuoftheday.com/techniques/naked-pairs-triples
- ↑ https://www.learn-sudoku.com/hidden-pairs.html
- ↑ https://www.sudokuonline.io/tips/advanced-sudoku-strategies
- ↑ https://www.sudokuonline.io/tips/advanced-sudoku-strategies
- ↑ https://pi.math.cornell.edu/~mec/Summer2009/Mahmood/Solve.html
- ↑ https://masteringsudoku.com/sudoku-tips-tricks/
- ↑ https://masteringsudoku.com/do-you-ever-have-to-guess-in-sudoku/
- ↑ https://www.gamesver.com/20-must-know-sudoku-tips-for-beginners/
- ↑ https://www.gamesver.com/20-must-know-sudoku-tips-for-beginners/
- ↑ https://www.gamesver.com/20-must-know-sudoku-tips-for-beginners/
About This Article
Did this article help you?
Ven P.
Apr 7