#677, December 20 - December 26, 2025:
The Weekly 'Unsolvable' Sudoku Puzzle
by Andrew Stuart
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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: BGH
Basics to 30.9
1 Step Solution
-- 5 @ C1 >> Solution
---- Unremarkable links to other cells or units.
---- I tried all the digits in the solution to see if there was a single cell solution.
---- I was hoping to learn something about hidden links to a single digit cell...
---- Unremarkable :-|
... by: Serban
# 677 A8=8 B9=2 C9=9 basics 25
1. G2=9 & G3=5 solve
2. G2=9 & C7=6 solve
... by: BGH
Basics 30.9
2 Step Solution
-- 2 @ H1 37.0
-- 3 @ B2 Solution
... by: Serban
# 677 A8=8 B9=2 C9=9 basics 25
1. Number 3 n=3 e=6 N=20 Nc=13 Ns=9 => B2= E7=3 solve
2. Number 6 n=3 e=6 N=21 Nc=18 Ns=1 => C7= E6=6 solve
Note : F8=H2=J9=6
... by: Serban
# 677 A8=8 B9=2 C9=9 basics 25
1. E2=7 & [J3=7 OR G7=7 ]solve
... by: Dieter
#677 - initially populated cells: 22 = 27,2 %
No solver used, solver = brain.
basics: A8=8, C9=9, B9=2
populated cells: 25 = 30,9 %
Strategy: numbers 8,9,2,3,6,7 occur most frequently, combine two cells.
combinations of G2 = (1,3,7,9) and H3 = (1,8,9)
after basic checks 4 matrices G2/H3 left: 1/9, 3/8, 3/9 and 9/8
G2/H3 = 9/8 solves with G1=3
Optimization:
G1=3 & G2=9 solve.
