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- A three-by-three Sudoku puzzle will take between 10 to 30 minutes to complete depending on your skill and expertise and the difficulty of the puzzle. Four-by-four Sudoku puzzles will take much longer to complete. As these puzzles are much larger than three-by-three puzzles, they usually take upwards of two hours.
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On my sudoku app (which highlights previously placed notes and numbers - very helpful) I've got average times of 2:42, 8:09, 13:49, and 24:24 for Easy, Medium, Hard, and Expert, respectively. Lots of variation in there though as my best times are 1:23, 2:34, 2:56, and 6:23.
- Overview
- Use a penci
- Note potential candidates in open square
- Scan the board to process the puzzl
- Start with the obvious single
- Revisit your candidates after you solve single
- Identify naked or hidden pair
- Move on to triples and quad
- Identify patterns in the remaining number
- Scan for x-wings to eliminate false candidate
Sudokus are phenomenal brain teasers, but if you find yourself solving easier puzzles in a jiffy, you may have moved on to harder puzzles only to discover that they feel impossible! The neat thing about sudoku is that there’s always another thing to try if you get stuck, and if you work carefully, you should be able to
through deductive thinking and logic alone. If you’re looking for some extra help on your next puzzle or you’ve come here out of a looming sense of despair that your most recent guess has ruined your current game, we’ve got your back!
This may seem obvious to you, but some folks don’t do this!
It’s possible for adept players to solve easier sudokus with pen, but for harder puzzles it’s going to help a lot if you use pencil. Harder puzzles require a lot of testing and note-taking, and being able to erase your marks will make it easier to visually process what you’re doing.
You can also write in the margins outside of the cells (the individual boxes of 9 squares inside of larger puzzle). Feel free to take notes or jot down reminders to yourself.
Using pencil also allows you to draw on the puzzle. If you use any patterns or uniqueness tests, you may want to visually track what you’re doing by circling or drawing around given cells.
Taking notes is mandatory if you’re solving complex puzzles.
Write potential candidates down lightly in open boxes. Most people use the corners, but you can use whatever method makes the most sense to you. This will help you narrow down choices, identify patterns, and avoid deadly patterns. If you’re a veteran, you probably already do this, but on the off-chance you don’t, it’s an essential way to play.
Candidates refer to the potential solutions for a given square. If you know that square has to be a 6, 4, or 8, then 6, 4, and 8 are all candidates.
It may feel like you’re making things harder by writing down every candidate, but the more information you have, the easier it will be to identify patterns and rule out incorrect answers.
Take a minute to look over the board and take it all in.
You’re probably not on a timer here, so don’t rush anything. Scan each cell to mentally map out and internalize the given numbers. This will get you comfortable with this specific puzzle, and keep you from making an early move that accidentally throws off the entire course of the puzzle.
There are two popular scanning techniques: one direction and two directions. Scanning in one direction involves viewing the cells from left-to-right and up-to down. Scanning in two directions involves looking at perpendicular rows and columns together to process early combinations.
If anything stands out to you as exceptionally obvious once you’re done scanning the given numbers, go ahead and fill in the squares you’re 100% confident in.
Naked and hidden singles are the easiest squares to solve.
A naked single is when a number can only go in one possible cell. A hidden single is when there is only cell for a given candidate. These singles are easy to identify, so spend a few minutes scanning each row, column, and cell for any squares with only one possible solution.
Cells refer to the collection of 9 squares that are inside of each sudoku puzzle.
For example, if there’s a 6 in the middle square of the center cell and a 6 in the righthand column of the top-center cell, but there is only one available square in the left-hand column of the bottom-center cell, then a 6 has to go there!
After you fill a square in, use the rule of one to find additional singles.
Whenever you solve a square, double-check the other candidates in the number’s row, column, and cell. Erase any notes you made that would violate the rule of one (there can only be one instance of a number in every row, column, and cell). This may give you even more hidden and naked singles.
After hidden and naked singles, pairs are the most helpful.
If you have two squares inside of a cell that could only be one of two numbers, you have a naked pair. This may seem unsolvable right now (since there’s no way to know which square takes which candidate), but they’re helpful for the cell you’re in. Use the pair to deduce which potential candidates exist for the other squares in that cell. By eliminating the pair, you may end up with a hidden single!
For example, let’s say you’ve got
written down in the top two rows of squares in the top right cell. This is a naked pair. On the top left cell, a 3 may be able to go in any square right now. Since your pair rules out the bottom row in the top left, you can cross those candidates out. If this reveals a single, you’ve got a new square to fill in!
Exhausting pairs and singles should reveal naked triples and quads.
Whenever you reveal 3 potential candidates across 2 or more squares in a given row, column, or cell, you’ve got a triple. You can use triples to reveal hidden singles the same way you used naked and hidden pairs. Once you’ve exhausted all of your pairs, take a look at the triples and quads you spot. At this point, with a large number of candidates crossed off of potential squares, you may be able to fill in additional squares.
There are a handful of patterns most players look for at this point.
Patterns refer to configurations of solved squares that help players regularly solve a sequence of candidates. There are a bunch of different patterns out there, but if you can spot one, they’ll typically help you solve some element of the puzzle that you’re struggling with.
A few common patterns include:
Corners (a collection of 4 solved squares in any of the 4 corners). Corner patterns help eliminate a ton of potential candidates in the rows and columns connected to it. Revisit these regularly to make sure you don’t provide a false solution.
(two rows or columns of a given candidate that are unequal in length). This pattern can help you isolate rows and columns to solve entire rows or columns of the puzzle.
Right angles (any 3 given numbers in an L-shape inside of a cell). Right angles give you a lot of information regarding the empty columns and rows in the cell they’re in, which can help you cancel out incorrect candidates in the adjacent cells.
The x-wing technique can be used to remove a ton of potential answers.
If you identify a set of 4 identical candidates that form a rectangle across multiple cells, you can use the x-wing technique. Since 2 identical numbers cannot be placed in the same row or column, you know that one “wing” has to be correct, and the other cannot be. Once you identify the x-wing, scan the cells, columns, and rows of the two wings and eliminate any candidates that would invalidate one of your wings.
Remember, this only works if the candidates are located in different cells. You cannot use an x-wing if one of the wing pairs are in the same cell.
This is easiest to visualize when the candidates are really close together, but the rectangular pattern required to use this technique could theoretically involve the 4 outermost corners of the puzzle.
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The objective of Sudoku is to fill a 9x9 grid made of squares (shown above circled in blue) so that each row, each column, and each full 9x9 square use the numbers 1-9. While solving the sudoku puzzle you can only use each number one time in the square, column, and row.
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I've been playing Sudoku now for close to a year. Not sure about the easy and medium, but I've been tracking on hard anywhere between 13 minutes to 30 minutes depending on difficulty. I see videos of pros taking around 30 minutes to solve hard. Sometimes the NYT hard puzzles are quite the challenge.
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Jun 18, 2024 · Step 1, Learn the setup. In a typical sudoku, you'll have a square grid of 9 large squares. Inside each of those larger squares will be 9 smaller squares. When faced with a puzzle, some of those smaller squares will be filled in with numbers from 1 to 9. More difficult puzzles will have fewer squares filled in.[1] X Research source The larger ...
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