#662, September 6 - September 12, 2025:
The Weekly 'Unsolvable' Sudoku Puzzle
by Richard Kröger, guest compiler
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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).
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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.
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Discussion...
Post an idea here...
... by: Frans Goosens
#662
Combination 2-digits cells
B9=1 No solution, Undo calculation
B9=7 Wrong, Undo calculation
B9=1 No solution, Fixed
C5=1 No solution, Undo calculation
C5=3 Wrong, Undo calculation
C5=1 No solution, Fixed
A2=2 ( D5=8 ) Solved,
Total solving time is : 44 sec.
Number of logical steps is : 5132
... by: Dieter
#662 - initially populated cells: 22 = 27,2%
No solver used.
basics: %
Strategy: Numbers 1,3,5,9 occur most frequently, combine two cells.
combinations of A3 = (5,6,9) and C3 = (3,5,8,9)
A3=9 & C3=3 solve.
... by: Serban
# 662 Basics to 22
1. Number 6 n=2 e=7 N=28 Nc=34 Ns=33 => A5=E4=6 solve
2. Number 8 n=2 e=7 N=30 Nc=57 Ns=2 => B1=F2=8 solve
3. Number 9 n=3 e=6 N=22 Nc=20 Ns=13 => A3=C4=9 solve
Note C4=H5=F6=9
... by: Yves
C1=5 & A5=6 solve
