Start Pause Reset
42 Comments Previous / NextHelp

Tough Sudoku for 23/September/2005


Choose a number, and place it in the grid above.

  1 2 3 4 5 6 7 8 9
Check out the latest post in the Sudoku Forum

Sudoku Solving Techniques

Submitted by: sudoku lover

Indicate which comments you would like to be able to see

First time entirely by logic, no guesses. 33 min
No guessing required.
Thanks for the explanations gb. I could't do 22.9, because I still can't do 20.9!
In your proofs for 20.9 you have to make an assumption (what I call a guess, that has to be tested) in point 4. Why did you pick b8 to test for No 2 out of all those numbers? There were three 2s in this row.
If you are too bored with my questions by now, don't answer :-)
hey rg and BW, how did you do it with no guessing? I still got stuck two thirds through.
Hi BW,
Step 4 was the hardest one in proof of 09/20 ! After examining all possibilities of alternatives between two choices, I had to investigate on alternatives between 3 choices...
That was why I said in comment that 09/20 took me blood sweat and tears...
As for 'guesses', they aren't More...
once again, this puzzle is isomorphic to 09/11 !
'As for 'guesses', they aren't but a way of writing : each step written down as a guess in a proof is in fact a geometric configuration in a certain 4-dimensional space...'
You are scaring me now :-)
Whatever they are (I call them guesses for personal use :) I hate toughs with them.
Thanks More...
20:10 Good time, okay movie, better book :p 1 guess, but the rest was pure brain hurting logic -off to take an aspirin-
I tell myself I am not guessing anymore. I am 'investigating a forcing chain'! Sounds better.
50+ mins 100% logic...
yay, no guessing required. in my opinion if guessing is required then its not a proper puzzle.
4:16.....with just enough 'guessing' to annoy a purist.
9 minutes 1 guess - so not perfect
6:36 no cheating!
gb's findings confirmed my feeling that there are very few really different ones among the toughies offered here. Maybe, there are just very few possible puzzles with so few cells filled in the initial position (21) in a nice symmetrical pattern. having a unique solution?
10:32, one guess... I use deduction for what's already in the grid, then I go to the old tried and true: every possibility as a potential number in every box... long but works - on occasion :)
24 minutes no guesses
Absolutely no need for cheating and no need for complicated logic on this one. This was one of the easier Toughs I've done.
55 minutes... no guess... whats the point of guessing?
46 minutes better almost by 14 minutes from the last time, hope i will get better.....
Who is the lady above the timer? It seems that if we look up her nostrils everyday, we should know who she is.
21:15 my fastest ever tough and no guesses. Honest
This is the first time that I have tried such a difficult Sudoku, and I'm happy to say that I managed to beat the Boss to the answer...!! :-))
Any tips Guys ?
I am new to this, but I don't see how this one could be done without guessing, and then retracing if the guess was wrong.
Definitely, Definitely.

Definitely, Definitely.
6:35 - I guessed more than I care to admit.
I agree with the above comment this was one of the easier tough puzzles. The best method is to do the puzzle online entering all of the possibilities and use the remove possibilities option.

Then start at the top right corner with the realization that there are two nines in one row and eliminating them from the other two boxes.

It flows easily from there.

13:18. i don't think any of the advanced calculus that i took is helping with any of these one bit.
10:23 How do you 6 min people do it so quickly? Do you think it all out in your head, or do you fill the whole thing up with all of the possibilities for each number? Do you have any other speed tips?
12:38 - no guessing
12:48..simple eliminations
Mar. 7, 2007.
14:46 May 20, 2007
21/May/07 2:23 AM
30 mts.
17/Aug/07 4:56 AM
Please Log in to post a comment.

Not a member? Joining is quick and free. As a member you get heaps of benefits.

Join Now Login