# Questions tagged [sudoku]

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.

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### 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:
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### 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 ...
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### 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; ...
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### 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 ...
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### 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?
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### 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 ...
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### 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 ...
868 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 ...
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### What will be the last Sudoku number to be filled?

When I am completing a Sudoku puzzle, there are always two last numbers to fill. Maybe it is just my puzzle solving approach or maybe it is inherent to Sudoku. I got wondering, would everyone who ...
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### Sudoku with only 8 predefined numbers

Have fun with my self-made Sudoku puzzle. Solve this Sudoku puzzle using the standard Sudoku rules: Fill any row, column and bold-framed area with the numbers 1 to 9. Hint: It is not as difficult as ...
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### Introducing: Sudoku-Janpu

This is an entry into the 29th fortnightly topic challenge - Retrograde Analysis. Scenario: Alice and Bob were playing a game of Sudoku-Janpu. Alice: I win. Bob: (looking at the board) Oh man, not ...
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### Sudoku embedded in a Kakuro

In addition to standard Kakuro rules, the grey shaded cells must form a valid Sudoku solution. One sum in this puzzle has been corrected from 28 to 23. Fortunately, it was in a location that nobody ...
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### Why does generating a Sudoku work in lines, but not in a random pattern?

So, I'll preface this by saying that I am not 100% whether this fits better here or on SO. That said: I've been trying to generate Sudokus using a backtracking algorithm to fill in the whole thing. ...
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### Sudoku board hint (part 2)

Don't worry, this is the last hint I'll ask for. I've looked for any position that could exclude others, and what's left is perfectly symmetrical. I've even tried mentally choosing some options to ...
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### Sudoku board position hint

As the title says, I'd like a hint (and an explanation why it is so) for the puzzle position in the attached image. I think I'm missing something really obvious but I can't figure it out. Again ...
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### Introducing Domidoku!

Come one, come all! Come see the new type of logic puzzle, the Domidoku! Here's a sample for all to try! The process is simple! First you solve the Sudoku and then you solve the Dominosa! ...
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### Revenge of the Cryptic Crossword Sudoku

This puzzle is inspired by Mattās excellent Cryptic Sucrosswordoku. Below is a sudoku as well as some cryptic clues. The clues lack enumeration and are in no relevant order. The solutions to the ...
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### Cryptic Crossword Sudoku

This puzzle is inspired by Mattās excellent Cryptic Sucrosswordoku. Below is a sudoku as well as some cryptic clues. The clues lack enumeration and are in no particular order. The solutions to the ...
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### Cryptic Sucrosswordoku

Maybe I'm a little bit evil. I've combined a couple of puzzle types in a novel way (to me, at least). I'll lay down some rules. The solution to the sudoku works exactly the way a normal 9x9 sudoku ...
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### What am I telling to you?

For my first question here, let's start cool with a little sketch. No, it's no hard brainstorming, no, it's not a revolution, yes, I had to start with something :)
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### Who am I??? Wait, isn't this a sudoku?

Jmw jrr qtlf tv ee M6SXr rro tr kz r tyr. Can you find out who I am? Hint 1: Hint 2:
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### Can a 9x9 sudoku with sum 45 and square sum 285 of (rows, columns, 3x3) not be valid? [closed]

I have created a program that checks if a Sudoku solution is correct. It tries to do so by checking the following: Rows, columns, 3x3 grids if the sum of the numbers is 45 $(1+2+3...+9=45)$ Rows, ...
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### Algebra Sudoku: Dozens

Alas, the grid deduction fortnightly is over, but my love for the genre remains the same - i.e. very high. So, here is another grid deduction puzzle. An algebra sudoku! I think the rules are fairly ...
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### Sum in A Sudoku

Color Blind version: Here's a sudoku puzzle with a twist! The numbers given in the squares are actually the sum of the numbers in that region. For example: 18= Sum of the numbers in the 4 yellow ...
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### Maximum Sudoku Puzzle

As most of you know, there is no Sudoku problem that has less than 17 number of starting clues with one unique solution. Imagine there is a sudoku problem that has $n$ number of starting clues with ...
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### What is guessing? [closed]

The whole difficulty of solving puzzles like sudoku is doing it without guessing. Well, either without any guessing whatsoever or with little enough that a human can still make retractions and come to ...
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### A Family Reunion

Names have been changed to preserve anonymity A group of 25 people, A to Y, arrived at Z's door to celebrate the family reunion. They each had something to show off. Z: I know you're all excited ...
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### Empty sudoku puzzle

The rules are the same as for a normal sudoku puzzle. The only thing different is that instead of numbers for clues, you have greater than/less than (> <) signs between the cells. Have fun solving!...
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### Happy 2017 Sudoku

This is a simple Sudoku. The only thing different from a regular sudoku are the symbols used: HAPY2017*. The snowflakes (a.k.a. asterisk) are like any other character. Wishing you a Happy New Year ...
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### A Page of Puzzling

I found this puzzle page from a newspaper and found it absolutely confounding. The sudoku had question marks and other things all over it, the logic puzzle made no sense, the cryptic crossword was ...
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### Christmas Sudoku

CHRISTMAS IS COMING!!! And to celebrate, here is a Christmas related sudoku: *A friend gave this to me and it took a long time for me to solve it. Thaks to @GentlePurpleRain for providing an updated ...
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### What is wrong with this Sudoku Game?

Before you, you have a game. There's something wrong with this game. Can you figure out what it is? ...
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### Help me to decorate my Christmas tree

Help me to decorate my Christmas tree with garlands of 7 bulbs. I want to fill in all the blank bulbs with numbers 1 to 7, so that each garland contains 7 different numbers. To make the tree more ...
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### A 16 Clue Sudoku Puzzle (but the kings can't be in check)

An entry in the 19th fortnightly challenge... Above is a 9x9 "chess" board with some pieces already laid out, your goal is to fill the board completely, following standard Sudoku rules (i.e. every ...
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### Sudoku as Poetry: A Tag-Fusion Masterpiece

This is an entry in the 19th fortnightly topic challenge: Unconventional Tag Fusion. I wrote some poetry for you, but it's hidden within this sudoku. Solve the puzzle and find the poem. For those ...
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### Why is this Sudoku Skyscraper Failing?

I'm attempting to write a program that solves Sudoku puzzles using a variety of techniques. Up this point, I've only implemented naked singles and hidden singles (for rows and columns). I've been ...
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### Can you solve the 7x7 (sudoku-ish) centered sums puzzle

I have come across this puzzle a few times in competitions and rally's, and it has troubled me because I cannot seem to find a good approach to solving it, either programmatically or numerically. And ...
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### When Sudoku met Ratio

Continuing on from my previous sudoku... I found an old piece of paper with a sudoku solution on it and vaguely remember solving it. This is unlike a simple solution however. You get no starting ...
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### Special 5x5 Sudoku-like table

This is a special 5x5 Sudoku-like table. Each row, column, and diagonal contains digits from 1 to 5 (including diagonals obtained by wrapping around the edges). To filter duplicates (by rotation, ...
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### An enigmatic sudoku

I entered the dungeon through a small, dark tunnel. After a seemingly endless walk I finally reached a small room. At the other side of the room, there was a big iron door. And in front of the door, ...
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### Hexagon (Sudoku-like puzzle)

This is the hexagon with digits to each row and diagonal which follow the rule : If the row and diagonal contains 5 triangles, it must contains all of the digits from 1 to 5. If the row and diagonal ...
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### Historical figure sudoku

This sudoku hides a famous person from the past. A solution will be accepted if the sudoku is solved (with steps to solve). The letters used are: abceloprt (in alphabetical order). PS. ...
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### Alphabetical Sudoku

Who loves fish? Okay that might sound a bit weird but don't worry, I am still sane. Maybe. To answer the question you must complete the Sudoku below. A word will appear in the highlighted box which ...
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### Sudoku solving strategy

I started solving the puzzle below and I got stuck at this point. I don't know how to continue solving this puzzle except using try and error. Does anyone know of a strategy to solve it?
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### Some Stratospherically Strenuous Sudoku

These three sudoku are particularly irksome, can you logically deduce the solutions to all (or any!) ...and provide your reasoning? They are all proper sudoku - each has a unique solution. They can, ...
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### Non brute-force Sudoku

The mypuzzle.org site (Difficulty = Hard, Date = 2016-07-12) has the following Sudoku puzzle. I filled in a three easy cells (in square brackets) but then got stuck. Aside from brute force, is there a ...
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### Amazing sudoku who can find hot numbers

Sudoku X Place the numbers 1-6 once in every row, column, diagonal, and 3x2 block. The diagonals form an X and are highlighted. Puzzle Text of puzzle ----------------- | . . . | 5 . . | | . . . | ...
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### There is a reason sudoku uses squares

There exists a 9x9 grid with the cells in one single row numbered 1-9 in order. The cells in the other 8 rows are initially empty. Note: The cells initially containing numbers can be in any one row;...