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#676, December 13 - December 19, 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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Supporter Members have access to all these puzzles going back to number 1.

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Saturday 13-Dec-2025

... by: Yves

one solving solution pairs : A6=7 & F8=8

Saturday 13-Dec-2025

... by: Dieter

#676 - initially populated cells: 25 = 30,9 %
No solver used, solver = brain.
basics: %
Strategy: numbers 1,2,5,6,7,8 occur most frequently, combine two cells.
combinations of H5 = (1,5,8) and H6 = (1,6,7,8)
after basic checks 2 matrices H5/H6 left: 5/6 and 8/6 > H6=6
H5/H6 = 5/6 solves with H1=4.

Optimization:
H1=4 & H5=5 solve.

Saturday 13-Dec-2025

... by: Serban

# 676 Basics to 25
1. Number 4 n=2 e=7 N=27 Nc=40 Ns= 37 => J8=4 solve

2. Number 5 n=3 e=6 N=22 Nc=16 Ns=7 => J3=5 solve
Page created on 03-May-2011, last modified on 30-May-2024.
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