... by: Serban
# 685 A6=7 Basics 251. B4=2 & B5=5 solve
@ Tomas
1. if A9=3 => UP 77 F3=G7=J18=0
2. if A8=3 => UP 27
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#685, February 14 - February 20, 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). |
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
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Discussion...
Post an idea here...Monday 16-Feb-2026
1. B4=2 & B5=5 solve
@ Tomas
1. if A9=3 => UP 77 F3=G7=J18=0
2. if A8=3 => UP 27
Monday 16-Feb-2026
... by: Frans Goosens
#685Combination 2-digits cells
A1=5 No solution, Undo calculation
A1=9 Wrong, Undo calculation
A1=5 No solution, Fixed
A2=1 ( B3=6 ) Solved,
Total solving time is : 35 sec.
Number of logical steps is : 4675
Sunday 15-Feb-2026
... by: Tomas
#685After Basics, to 25 numbers,
A9=3 leads to contradiction => A8=3.
Solved
Sunday 15-Feb-2026
... by: Serban
# 685 A6=7 Basics 251.Column 1 n=3 e=6 Nc=19 Ns=17 =>
1a. E1=7 solve
1b. A1=5 & F1=2 solve
2. Number 9 n=2 e=7 N=30 Nc=65 Ns=9 =>
2a. A9=G1=9 solve
2b. A9=9 & F3=4 solve
2c. A9=9 & F1=2 solve
Saturday 14-Feb-2026
... by: Dieter
#685 - initially populated cells: 24 = 29,6 %No solver used, solver = brain.
basics: A6=7
populated cells: 25 = 30,9 %
Strategy: numbers 6,7,4,5,8 occur most frequently, combine two cells.
combinations of C1 = (4,5,6,9) and D4 = (1,2,4,6,9)
after basic checks 2 matrices left: C1/D4 = 4/4 and 4/6
C1/D4 = 4/4 solves with B8=8
Optimization:
C1=4 & B8=8 solve.