Solver App for Android and iPhone
Strategies for Number Puzzles of all kinds
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Feedback and Questions

I've received a lot of interesting comments and questions from Sudoku fans over the last few years and this page is where I try to answer them. Please feel free to drop me a note on the side of the page or try the Facebook comment box. Or you can email me directly at .

Post a Comment or Question here...
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Any Sudoku you want to publish here for easy loading into the solver - 81 characters, use '.' or '0' for unknowns.

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private - email comment/question directly to Andrew Stuart, don't display here

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Many thanks to all the people who have helped improve the solvers and strategies with their feedback!

Tuesday 19-Aug-2014

... by: NiZhiyang, China

I think the Sudoku X unsolvable example is TOO EASY!Let me give you a hard unsolvable example.
See,this is harder than yours!

Andrew Stuart writes (19-Aug-2014):

That is harder, but I wasn't really trying. Here are some equivalent, I hope. Load in the Sudoku X Solver.


Do leave an email address next time!

Thursday 14-Aug-2014

... by: john, us

Why is the Sudoku board now so small and I can't zoom it?

Andrew Stuart writes (19-Aug-2014):

Did you perhaps "zoom" the browser? To reset, for example, in Firefox, it's here:
Zoom reset

Wednesday 13-Aug-2014

... by: Larry Doe, Hyde Park, NY

Load Sudoku:

Today's daily sudoku puzzle reduces to this: ..5.2.4...
Solution count says 1 solution but it actually has two solutions.

Andrew Stuart writes (19-Aug-2014):

Probably a bit late now, bit I'd love to see both solutions. I can detect if there has been a mistake, but I do promise you, in nine years, I've never made a double solution puzzle! ; )

Wednesday 13-Aug-2014

... by: Claude, Europe

I cannot find your app in the store, correct ?

Thanks for your answer

Andrew Stuart writes (23-Aug-2014):

Yes, one of our annual Apple agreements expired. I'm trying to understand the Apple process to get this sorted, not very easy.
Hopefully all apps will be back up either later today or next week if I have to wire money.

Wednesday 13-Aug-2014

... by: Mina, X

Excelent! Work, thank you !

Andrew Stuart writes (19-Aug-2014):


Sunday 10-Aug-2014

... by: Sundeep, India

Hi Andrew,
Thanks to this wonderful site, I am learning more tricks.
One small modification I would suggest (as I made that mistake) - could you make the link in (See Strategy Overview documentation) below the solver open in new tab/window by default? Or some other workaround - my issue was that manual edits (possible numbers inside unfilled squares) disappeared when I accidentally clicked the link and came back to the page.

Andrew Stuart writes (10-Aug-2014):

Hi, thanks for the idea. The right side strategies already open a new page, and the puzzle board should save itself (as a cookie) if you accidentally close or move away. Might not catch every last change, depends. I've added a new target page/tab for those other links to the strategy overview though.

Wednesday 6-Aug-2014

... by: 35436363, europe

Load Sudoku:

I want to have a Kakuro Solver. The Str8ts Solver says always: Oops - you got an error on the board (0)

Andrew Stuart writes (10-Aug-2014):

Yes, I'd like to add a Kakuro solver. I have the generator, which is half the job. All depends on getting time ; )
Kakuro won't work in any of the other solvers...

Tuesday 5-Aug-2014

... by: pat field, wisconsin

Dear Andrew,

Love your site. But recently I have been having problems when I access it on Chrome (no problems on Internet Explorer, same computer).

Problems: cannot activate Auto Clear

Delay in entering data from left screen to main screen: it takes one more keystroke for the (last) entry to show up. I am also experiencing a one keystroke delay as I type this complaint (which is disconcerting).

I'm a big fan, nevertheless.


Andrew Stuart writes (10-Aug-2014):

That's very strange behaviour. It does sound like a chrome-client side thing. No having any problems on my chrome, nor have I added anything recently that should effect it. Difficult to say. Tried clearing your cache?

Tuesday 5-Aug-2014

... by: TimCinOR, Oregon

Great site!

Especially thanks for the stepper, and the explanations of the strategies. I've got a puzzle that has some strategies for me to learn.


Wednesday 30-Jul-2014

... by: Robert Campbell, USA

I cannot maneuver through your opening screen that has too much information on it for me to know where to start. Please offer some help. I want to learn how to do easy sudoku

Andrew Stuart writes (31-Jul-2014):

Hi Robert
Start here:

I agree, I need to make it easier to find that page from the start

Best of luck solving!

Thursday 17-Jul-2014

... by: Kai Bachmann, Austria

Load Sudoku:

This Sudoku uses three times the XY-Chains strategy (solving steps 11, 12 and 13) with the same cells C3, C4, C5, F4 and F5, changing only the starting/ending point of the chain, and eliminates candidates 4 in cell C7, 1 in cells A5 and B5, and 2 in cell F6.
A nice example to show how a same chain, varying its starting/ending point, can exlude many different candidates.

Andrew Stuart writes (24-Jul-2014):

An excellent example, well found
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