Sudoku puzzles are a fun and challenging way to keep the mind sharp. But have you ever wondered if a Sudoku puzzle can be unsolvable? As an experienced Sudoku player, I wondered the same, so I researched while also applying what I’ve learned from playing this puzzle for years.
As a rule of thumb, all Sudoku puzzles are solvable. When players say that the puzzle is unsolvable, most of the time, it is because the puzzle is too hard or they are missing something. However, while rare, there are times when these puzzles are unsolvable, and this happens because of some errors on the manufacturing side.
In this blog, we will explore if Sudoku puzzles are unsolvable. We will also discuss why this happens. So join me in discovering the secrets of these fascinating puzzles.
Can a Sudoku be unsolvable?
Sudoku puzzles can be unsolvable only if there is an error on the manufacturing side. Incorrectly generated puzzle happens because of human or machine error. For example, they are printing the wrong numbers on the boxes. However, because most puzzles are now machine-generated, these instances are becoming rare.
When a person says that a Sudoku is unsolvable, they usually talk like this because they have no idea how to solve the puzzle.
This is because Sudoku requires multiple skills to learn and master to solve more complicated puzzles.
Let’s see which skills you should improve on.
Here are some skills you to make your unsolvable puzzle, solvable:
This involves looking for rows, columns, and subgrids that already contain a specific number and using that information to eliminate that number as a possibility in other squares.
2. Filling in the Naked Singles
This involves finding a square with only one possible number and filling it in.
3. Hidden Singles
This involves looking at each row, column, and subgrid and finding a square that can only be filled with a certain number.
4. Intersection Removal
This technique involves finding a number that only appears in two squares in a row, column, or subgrid and eliminating that number as a possibility in other squares in that row, column, or subgrid.
5. Using Guessing and Backtracking
This method of solving the puzzle involves guessing a number in a cell and then using the logic to deduce a correct number if the guess is incorrect.
6. X-Wing, Y-Wing, Swordfish
These are more advanced techniques that utilize patterns in the rows and columns to deduce the solution.
There are more Sudoku techniques, and these are only examples.
Learning these techniques can take a very long time to master. Thus, it is essential to solving puzzles that are only a bit higher than your current skill level.
That way, you can still solve the puzzle while improving your skills.
Recommended Read: One of the ways to get better at Sudoku is to know the common mistakes beginners make. Thus, if you’re interested in learning about those common mistakes, I created a post discussing it here: Why do you keep failing in Sudoku?
So what’s my point here?
A Sudoku puzzle can have no solution only if there is an error on the manufacturer’s side, which is rare. Most of the time, people say that their Sudoku has no solution because the puzzle doesn’t fit their skill level. Thus, almost all Sudoku puzzles available online have a solution.
My point here is that almost all the puzzles you can get in stores are solvable. In fact, manufacturers ensure this is the case before releasing them.
We will discuss this later, but for now, you have to understand that most puzzles are solvable. People are only saying that the puzzle is unsolvable because their skill level doesn’t match the puzzle’s difficulty.
Can a Sudoku Puzzle be Wrong?
Sometimes, Sudoku puzzles are wrong, and it usually happens because of a human or machine error. For example, incorrectly generated puzzles or misprinted numbers. However, these are rare, and most of the time, the puzzles are unsolvable because their difficulty doesn’t match the player’s level.
I know it can be hard to accept, but most of the time, the puzzle you find unsolvable is because the puzzle is too complicated at your current level.
Even advanced Sudoku players encounter problems like this. Even I, who plays a lot of Sudoku in my free time and knows a lot of solving techniques, have some days where I can’t solve a puzzle.
And this is normal.
There are also Sudoku puzzles that can be solved in multiple ways. Usually, these puzzles are easier as there are many ways to finish them. On the other hand, sudoku puzzles that only have one way to solve are more challenging as you must be highly cautious when placing the numbers.
But there is more to it. While rare, there are some Sudoku puzzles that are wrong. In short, there is no way to solve them.
However, through experience, I never encountered such a puzzle, as these puzzles are so rare.
These puzzles are caused by an error on the manufacturing side. Furthermore, most Sudoku puzzles are computer generated with complex algorithms to ensure it doesn’t happen.
However, since these are computer generated, there is some rare instance where the generated puzzle is unsolvable. So, these errors are usually caught before getting into the public.
This also means that while humans are checking these puzzles, there will be times when they can create some errors causing them to approve an unsolvable puzzle.
As you can see, computer-generated puzzles and quality control reduced the likelihood of getting an unsolvable puzzle to almost zero.
However, some errors can still get through these quality checks.
For example, errors in printing can cause a number to be placed on the wrong box. This changes the puzzle into something different, which may become unsolvable.
While these errors can cause unsolvable Sudoku puzzles, it is crucial to understand that there is only a tiny chance for the puzzle you are solving to be that way.
The complex computer algorithms and human quality control checks ensure that the puzzles you solve are solvable.
Thus, if you find the puzzle you’re solving challenging, the best thing to do is take a break, learn and hone your Sudoku skills, and return to it on another day.
Of course, if you want an easy path, there are many Sudoku communities online where you can share your puzzle, and others can solve it for you.
However, I don’t recommend this approach, as the moments you solve a difficult puzzle make this game fun.
What’s next? We know that solving a Sudoku puzzle is hard. Thus, one might wonder if Sudoku is for everyone or whether IQ affects your Sudoku-solving skills. I created a post discussing these here: Is Sudoku for Everyone?