#649, June 7 - June 13, 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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Discussion...
Post an idea here...
... by: BGH
2 Step Solution after Basic Deterministics for #649
1. 7 @ E6 (Column 6 has Unit 7's in rows B & E, one of the two 7's is in the solution)
2. 6 @ F1 (16 pair in F1, Intersecting Triple Column 1, Quintuple in Row F, ripples from there)
--- One of the two digits is in the solution.
... by: Dieter
#649 - populated cells = 23 = 28,4%
basics: G9=4, J3=7, D6=8
populated cells = 26 = 32,1%
strategy: try to get hidden pairs or triplets. No solver used.
combinations of C4 = (2,4,7,9) and C5 = (4,8,9) as numbers 4,7,8 are populated most.
2 matrices left after basic checks: C4/C5 = (2/8) and (7/9)
start with C4/C5 = (7/9) as 50,6% populated: solves with F1=6
Review:
C5=9 & F1=6 or C4=7 & F1=6 solve.
... by: Serban
#649 D6=8 G9=4 J3=7 Basics to 26
1. Number 6 n=3 e=6 N=18 Nc=9 Ns=6 => F1=6 solve
1. Number 7 n=4 e=5 N=15 Nc=6 Ns=2 =>B9=7 basics to 44
2. XY-Wing 129 [H16,F6] => F1<>1 => F1=6 solve
1. Number 8 n=4 e=5 N=15 Nc=10 Ns=9 => A8=8 basics to 38
2. X-chain x=2 => [F1,H2,C4,E7,A9]<>2 => E2=F9=2 basics to 52
3. XY-Wing 129 [H16,F6] => F1<>1 => F1=6 solve
