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#677, December 20 - December 26, 2025:
The Weekly 'Unsolvable' Sudoku Puzzle

by Andrew Stuart
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.
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Saturday 20-Dec-2025

... 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.
Page created on 03-May-2011, last modified on 30-May-2024.
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