... by: Serban
# 699 Basics to 221. B7=3 & G3=1 solve
2. E5=4 & G5=9 solve
3. E5=4 & H5=3 solve
4. B8=1 & D8=4 solve
5. B2=9 & D6=5 solve
6. G5=9 & H6=6 solve
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#699, May 23 - May 29, 2026:
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WARNING: This is the Weekly 'Unsolvable' Sudoku, rated above 'Extreme'. This is currently unsolvable by my solver, except perhaps with trial and error strategies. Using the solver will not help you. (much). |
Changes March 2026
Due to the introduction of Forcing Nets many Weekly Unsolvable puzzles can now be solved. I have flagged all the Sudoku ones which are solvable. I am struggling to make any new ones so we'll have to see if the Weekly can continue. The point of the Weekly was to provoke discussion and new ideas, so that is progress. But my solution is unlikely to be optimal so alternatives are welcome.Archive
Each week a new 'unsolvable' will be published and the previous will be accessible here from this archive section. If you like very tough puzzles, these are for you.Share and Enjoy
Supporter Members have access to all these puzzles going back to number 1.
Discussion...
Post an idea here...Sunday 24-May-2026
1. B7=3 & G3=1 solve
2. E5=4 & G5=9 solve
3. E5=4 & H5=3 solve
4. B8=1 & D8=4 solve
5. B2=9 & D6=5 solve
6. G5=9 & H6=6 solve
Saturday 23-May-2026
... by: Frans Goosens
#699With trial and error
Combination A3=267 and I9=148
************************************************************
A3=2 I9=1 Wrong, Undo calculation
All reset to initial position
************************************************************
A3=2 I9=4 Wrong, Undo calculation
All reset to initial position
************************************************************
A3=2 I9=8 Wrong, Undo calculation
All reset to initial position
************************************************************
A3=6 I9=1 Wrong, Undo calculation
All reset to initial position
************************************************************
A3=6 I9=4 ( A9=9 ) Solved,
Total solving time is : 74 sec.
Number of logical steps is : 8859
Saturday 23-May-2026
... by: Dieter
Oooops!Just have read Andrew's comment. My solution is the one for the puzzle before 8:45am.
Saturday 23-May-2026
... by: Dieter
#699 - initially populated cells: 24 = 29,6 %No solver used, solver = brain.
basics: J8=9, J1=8
populated cells: 26 = 32,1 %
Strategy: numbers 1,8,9,3,5,7 occur most frequently, combine two cells with almost same candidates.
combinations of A2 = (4,5,7,8,9) and A7 = (2,4,8,9)
after basic checks 5 matrices left: A2/A7 = 5/2, 5/9, 8/2, 8/4, 8,9
A2/A2 = 5/9 solves with E8=2
Optimization:
E8=2 solves.
Saturday 23-May-2026
... by: Yves
B3=7 ...Or G6=7
Saturday 23-May-2026
... by: Andrew Stuart
Sorry, after realizing the first puzzle solved, as of 8:45am on Saturday, I swapped out the puzzle for this one. Still knock on effects in my files from Forcing NetsSaturday 23-May-2026
... by: Serban
# 699 J1=8 J8=9 Basics to 261. E8=2 solve
2. D2=E5=3 solve
3. D3=6 solve
4. B3=7 solve