Solver App for Android
Strategies for Popular Number Puzzles
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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. I'm also directing Str8ts feedback here. Please feel free to drop me a note on the side of the page. 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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Many thanks to all the people who have helped improve the solvers and strategies with their feedback!

Saturday 22-Jan-2011

... by: Ward, USA

Please turn off the auto-tabbing when entering numbers in the small grid. Very confusing and tough to negotiate now.

Andrew Stuart writes:
I've had so many requests to put auto-tabbing in over the years ... :)
I've added an check box to the new version.
Don't forget the arrow keys now work and help you move around the grid

Friday 21-Jan-2011

... by: Bill Volz, USA Midwest

Key strokes for loading a new Sudoku have changed. The worst is the total loss of entries if the tab key is pressed to leave the last square empty.
Entering a number now also advances the active square making it harder to correct an error using the delete followed by the correct entry.
Please restore the old system.

Andrew Stuart writes:
There was a bug, which I've fixed this morning. If you tabbed the last cell you went to the example picker which activated the example puzzle. Shouldn't do that now. I've also added tick box to activte/turn off auto tabbing.

You might need to refresh the pages to pick up the new version.

Thursday 6-Jan-2011

... by: Marvin Shapiro, Maryland, US

Load Sudoku:


Thanks so much for your sudoku website!

I wrote my own sudoku solving program (in Java) and, to check it out,
used the 50 hardest puzzles from a Will Shortz book.
Since my rules were sufficient to solve them all, I figured I was done.
I also figured that the chaining rules I had read about--and had NOT programmed--just
never really occurred. Wrong!

On vacation (I never do sudoku at home) I ran into an "expert" puzzle
and got as far as follows:
where I was stuck. When I got home I found that my program was stuck there, too.

So I DO have to look for chaining, which I don't think should be too difficult.

BTW, I like your way of saving the puzzle as a cookie. I hadn't thought of that.


Marvin Shapiro

Andrew Stuart writes:
Hi Marvin

Glad you found it useful. Email me if you want a bigger stock of very hard test Sudoku puzzles
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2015 2014 2013 2012 2011 :1 2 3 4 5 6 7 :2010 2009 2008 2007 2006
Thank-you everyone for all your questions and contributions.