Stack Exchange Network

Stack Exchange network consists of 174 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

A Sudoku is a puzzle consisting of a grid to be filled with symbols, such that each constraining unit contains each symbol exactly once. The typical example is a 9x9 square to be filled with the numbers 1 to 9, where the constraining units are rows, columns, and 3x3 blocks.

4
votes
9answers
3k views

Sudoku false positive (wrong move)

I'm new to Sudoku puzzles. I tried solving the one above but my last move was flagged as a wrong move(highlighted red). I believe it is a false positive since the $6$(highlighted red) I inserted is ...
5
votes
1answer
177 views

A Quick Sudoklu

Across ...
3
votes
1answer
134 views

What do you get when you mix a crossword and a sudoku?

For this CrosSudoku puzzle you must completely solve the sudoku grid below. To start the sudoku you must first figure out the crossword clues to get the starting numbers. Clue notation: x and y are ...
4
votes
4answers
166 views

Why is the following 7 in Sudoku a mistake - Newbie

I'm a newbie at sudoku. Why is the following 7 in Sudoku a mistake?
8
votes
1answer
177 views

Unusual Sudoku Puzzle

Find the solution to this Sudoku puzzle. The only problem is there aren't any normal Sudoku clues. Instead there are only some cryptic clues. What is the solution and how does the puzzle work? Edit: ...
3
votes
2answers
165 views

Stuck on this Sudoku!

I have tried every trick I can think of... where am I going wrong?
4
votes
1answer
135 views

Is solving a puzzle using uniqueness invalid? [duplicate]

(I don't know if this is appropriate to ask here, since it's a bit of a soft question about puzzles, rather than a puzzle itself. I'm not certain about the tags either.) When I was first introduced ...
1
vote
2answers
173 views

How do I proceed with this Sudoku puzzle?

Pairing elimination is done. What's next?
1
vote
1answer
227 views

Generate a sudoku puzzle with minimum number of entries that has exactly $k$ solutions

Is there an algorithm to generate a sudoku puzzle having the minimum number of entries that has exactly $k>1$ solutions? What is this minimum number of entries, as a function of $k$? Given that ...
2
votes
2answers
303 views

Examples of sudokus with two solutions [duplicate]

I need some examples of sudokus having more than one solution. Do these puzzles have any common things?
0
votes
1answer
69 views

What should be my next valid move?

That's the stage I'm now. I am looking at G block (one in left down corner) 4,5 value. I couldn't decide if it should be 4 or 5. How do I decide? And, am I looking at the right place? Any alternate ...
11
votes
1answer
247 views

The Vowel Sudoku Challenge

This is an entry into the Fortnightly Topic Challenge #36 Here is a partially filled in Sudoku-like board involving the five vowels: As with real Sudoku, no vowels in any 9-square box or along any 9-...
47
votes
2answers
2k views

R.H.P.C. crossword puzzle

This is an entry into the Fortnightly Topic Challenge #36 I got a ticket to the Red Herring Puzzle Club in the middle of the street. There was just a guy giving them out, like some advertisement ...
4
votes
1answer
175 views

Finding a number in this sudoku

I have been trying this sudoku for nearly 5 hours now but im unable to find any number further...If anyone could help me out i would be really grateful.. Note: The numbers in black are the prefilled ...
5
votes
2answers
183 views

Do multi-way jigsaw sudoku exist?

A Jigsaw sudoku is like a regular sudoku, but with uneven shapes instead of 9 squares. However, they still have the normal rules for rows and columns. Would it be possible to have a jigsaw sudoku ...
23
votes
2answers
746 views

Slightly Odd Sudoku

Someone I find very trustworthy continues to insist that this is a valid Sudoku board. It's been a while since I've played, but surely there's a couple of things off here, right? Alright, so that ...
11
votes
1answer
409 views

An Incomplete Puzzle

I'm sorry to offload some of my work as the puzzle creator on to you solvers. (No, I'm not.) At least there's only one clue missing, right? EDIT: When the puzzle is ready to be solved, there will be ...
4
votes
1answer
186 views

Trying to build a sudoku related puzzle box, struggling to ensure that there's only one solution

I want to build a specific puzzle box. The physical side I have down, but I'm struggling with ensuring that there's only one valid solution. The box consists of 9 freely rotating bands, inscribed ...
0
votes
1answer
391 views

Help solve sudoku

I did solve this sudoku in 24 minutes, but I had to guess from this part out. I'm using a website to display this sudoku a lot neater than the original site. I can solve plenty of sudokus, but the ...
3
votes
0answers
251 views

How to solve this puzzle?

I have solved the sudoku. Scratching my head on the second part. Any hints? It is not picked from any competition. One of my office colleagues usually post these types of puzzles on emails for fun ...
4
votes
4answers
203 views

Do there exist Graeco-Latin Square style puzzles?

Sudoku, KenKen, and Skyscrapers are three examples of Latin square puzzles. In all three, players are challenged to complete a Latin Square, a NxN grid (typically 9x9) in which the numbers 1-N appear ...
62
votes
2answers
4k views

Happy Pi-Day! Try to solve this “PiDoku”

To celebrate the Pi-Day (3/14) adequately, a challenging math puzzle must not be missing. Rules: Fill in the numbers 1-9 exactly once in every row, column, and region. On top of that, you need to ...
13
votes
2answers
1k views

Sudoku Construction Question

I'm one of a group of people building a big puzzle hunt. I have what I think is a pretty good idea for a puzzle, but I'm having trouble constructing it. Basically, what I need to do is make a sudoku ...
6
votes
2answers
194 views

Integers in Cells puzzle (sudoko-like)

All the whole numbers 1−9 are placed in the 9 triangular cells. A negative sign is placed in front of some numbers. The letters A−F are products of 3 or 5 of the numbers. Find all possible ...
1
vote
2answers
184 views

Sudoku puzzle - where to go next?

Above is a link to a half-solved sudoku puzzle. I tried to fully solve it but just cant figure out what to do now. Source: Sudoku-Branium studios It is an app on google playstore.
-1
votes
2answers
226 views

SUDOKU What next? [closed]

I have solved up to this point. How do I proceed without guessing?
4
votes
1answer
1k views

Do I need to guess from here on this sudoku?

I keep staring at this sudoku puzzle and can't seem to find the next move. Is the next move a guessing move? I thought sudoku always has clear solutions, you just need to figure them out.
-5
votes
1answer
887 views

Sudoku puzzle #1

Please solve the following sudoku puzzle (from Wikipedia):
39
votes
1answer
2k views

Japanese Fusion Alphabet Soup

The Dish... ...is an intriguing blend, with a base of classic Western flavours, and a twist of the Orient at its heart. The Ingredients... ...are diverse and are combined in such an unexpected - ...
16
votes
2answers
874 views

Save the Eggs! - An Angry Birds Puzzle (Part 2)

⬅️ Angry Birds 1 After saving the eggs, the birds are more cautious. Good News! You can finally relax and enjoy the birds’ hospitality. Unfortunately for you, you’re not the only visitor in town. ...
10
votes
1answer
1k views

Sudoku with chess queen rules

This is a unique sudoku. With Rules : Common sudoku rules apply. Numbers 1,2,3 have an additional rule, they are also chess queens. If all others numbers removed, the 1s do not attack each other ...
5
votes
3answers
976 views

Sudoku and guessing : theory?

It has been proven that the minimum number of givens for a uniquely solvable classic 9x9 sudoku is 17. The usual solving method followed by people is : Fill all the cells where you are sure there is ...
24
votes
1answer
2k views

This is a crossudoku

So, this is a crossudoku. It is the same as a sudoku - same rules apply. However, you have been given crossword-like clues for part of the numbers on the grid. Some of the clues may have multiple ...
13
votes
2answers
512 views

Double n-queen puzzle, with sudoku rules

Put 9 blue queens and 9 pink queens, with rules : If the blue queens removed, each pink queens do not attack each other. If the pink queens removed, each blue queens do not attack each other. Each 3×...
4
votes
2answers
321 views

What should be used to solve the next step of this sudoku puzzle

How to solve the next step in this sudoku ? I tried X-wing, hidden pairs and many other popular techniques found here http://hodoku.sourceforge.net/en/tech_hidden.php
5
votes
2answers
764 views

Special Sudoku, with windows pattern

Solve this Sudoku, with rules : Every blue square means, it is the left-top of a 3x3 block with each numbers [1 to 9] appearing only once there. There is only one unique solution. Check the example. ...
1
vote
4answers
249 views

What technique should be used to continue with this sudoku

I searched for x wing and the bone. Im thinking colors but not sure.
7
votes
1answer
762 views

Solve this Subtraction sudoku!

This is subtraction sudoku. The rules are basically the same as common Sudoku, but with a few additions. In the row, the number in the orange box is the difference when its left side (sum of 3 ...
9
votes
2answers
458 views

Tetromi-nuri-doku

Note: This puzzle was inspired by the one here, by Mike Q. Every square in the grid above, when the puzzle is complete, has a number between 1 and 9 in it and either is shaded or is not. Each 3x3 ...
6
votes
3answers
1k views

What do chess and wordoku have to do with each other? - Clue Thirty-One

<<---First clue <---Previous clue (?) "Aha! That's it," you exclaim, still holding the papers. "The answer is obviously [redacted]." Having figured out the answer, you start looking over the ...
3
votes
2answers
383 views

Another Determinant Sudoku

sudoku-determinant have been described well here : The Determinant Sudoku I have created another one. Number in the center is the value of the determinant Numbers 0 to 10 are the values of the ...
5
votes
2answers
374 views

Sudoku difference between x wing and double pair

Double Pairs and X Wing are listed as different techniques here (former is a medium and later a master technique). The only difference I can see is double pairs are restricted to two neighbor blocks ...
0
votes
2answers
900 views

Arrange to get sum of 450 when it is added row wise and column wise

I just came across a maths puzzle,where i should get the sum of 9 numbers(multiples of 10) to be 450 both horizontally and vertically in a 9x9 matrix. Picture attached for reference:
5
votes
1answer
235 views

An EMIRP Game/ Puzzle for Prime enthusiasts

As most math enthusiasts know, EMIRPs are Prime Numbers which are also prime numbers when reversed. Like 17 which when reversed to 71 is also a prime number. Here is a Game or Puzzle based on 5 ...
7
votes
5answers
472 views

The Numberphile Heist (part 1)

Hello Puzzling Stack Exchange! While part 1 of the PSE School of Enigmatics remains unsolved, I've got part 1 of another puzzle series for you to solve. I'm in no way affiliated with Numberphile; ...
15
votes
2answers
609 views

Tetromino Sudoku

An entry in Fortnightly Topic Challenge #32: Grid Deduction Hybrids The grid below, when filled in, forms a valid Sudoku grid. It can also be filled in like a LITS (nuruomino) puzzle without the 1x4 ...
11
votes
1answer
2k views

Nested sudoku in entrance exam

My university set this question in 2013's entrance exam. Also the red boxes include from 1 to 9. What's the solution for this sudoku?
32
votes
3answers
2k views

The Determinant Sudoku

The determinants of $2\times 2$ matrices are calculated this way: $$\det\begin{bmatrix}a & b \\c & d \end{bmatrix}=ad-bc$$ And here's the sudoku-determinant puzzle: What's the solution for ...
7
votes
1answer
314 views

Skeleton sudoku, the second

I've already set one skeleton Sudoku. Here's a rather harder one. (Nonetheless, it should be within the realms of what can be done by hand; I solved it manually myself to verify that there was only ...
8
votes
2answers
587 views

A spartan skeleton Sudoku

A skeleton crossword is a crossword where the black and white squares aren't given; you have to deduce them. Here's a generalisation of that idea to the Sudoku puzzle. Here's a 4 by 4 grid, with four ...