Feb 06 - Very Hard
Puzzle Copyright © Kevin Stone
Share link:
Reasoning
R4C1 can only be <7>
R6C4 can only be <7>
R6C9 can only be <9>
R4C6 can only be <9>
R9C6 can only be <7>
R9C4 can only be <2>
R7C5 can only be <9>
R1C7 is the only square in row 1 that can be <6>
R4C5 is the only square in row 4 that can be <2>
R6C5 is the only square in row 6 that can be <6>
R8C8 is the only square in row 8 that can be <6>
R3C7 is the only square in column 7 that can be <2>
R3C9 is the only square in row 3 that can be <7>
Intersection of row 3 with block 1. The values <49> only appears in one or more of squares R3C1, R3C2 and R3C3 of row 3. These squares are the ones that intersect with block 1. Thus, the other (non-intersecting) squares of block 1 cannot contain these values.
R1C1 - removing <4> from <23458> leaving <2358>
R1C3 - removing <4> from <2348> leaving <238>
Intersection of row 8 with block 7. The value <8> only appears in one or more of squares R8C1, R8C2 and R8C3 of row 8. These squares are the ones that intersect with block 7. Thus, the other (non-intersecting) squares of block 7 cannot contain this value.
R7C1 - removing <8> from <23458> leaving <2345>
R7C2 - removing <8> from <358> leaving <35>
R7C3 - removing <8> from <23478> leaving <2347>
Squares R7C2 and R9C1 in block 7 form a simple naked pair. These 2 squares both contain the 2 possibilities <35>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the block.
R7C1 - removing <35> from <2345> leaving <24>
R7C3 - removing <3> from <2347> leaving <247>
R9C3 - removing <3> from <39> leaving <9>
R8C2 can only be <8>
R8C3 can only be <7>
R8C7 can only be <9>
R3C2 is the only square in row 3 that can be <9>
R7C7 is the only square in row 7 that can be <7>
Intersection of column 8 with block 3. The value <1> only appears in one or more of squares R1C8, R2C8 and R3C8 of column 8. These squares are the ones that intersect with block 3. Thus, the other (non-intersecting) squares of block 3 cannot contain this value.
R2C7 - removing <1> from <135> leaving <35>
Squares R2C2 and R2C7 in row 2 form a simple naked pair. These 2 squares both contain the 2 possibilities <35>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the row.
R2C3 - removing <3> from <138> leaving <18>
R2C8 - removing <5> from <158> leaving <18>
Squares R2C7 and R9C1 form a remote naked pair. <35> can be removed from any square that is common to their groups.
R9C7 - removing <35> from <135> leaving <1>
R5C7 can only be <5>
R5C5 can only be <3>
R2C7 can only be <3>
R4C9 can only be <1>
R2C2 can only be <5>
R4C4 can only be <5>
R5C3 can only be <8>
R3C5 can only be <5>
R6C6 can only be <8>
R6C1 can only be <3>
R5C6 can only be <4>
R7C2 can only be <3>
R3C8 can only be <1>
R1C4 can only be <4>
R2C8 can only be <8>
R2C3 can only be <1>
R5C4 can only be <1>
R1C6 can only be <3>
R3C1 can only be <4>
R9C1 can only be <5>
R9C9 can only be <3>
R1C3 can only be <2>
R7C8 can only be <5>
R1C9 can only be <5>
R3C3 can only be <3>
R7C1 can only be <2>
R7C3 can only be <4>
R1C1 can only be <8>
R7C9 can only be <8>
Today's Sudoku Puzzles
All daily items change at midnight GMT – set your local time zone.
Note: BrainBashers has a Dark Mode option – I recommend not using your browser's dark mode or extensions for BrainBashers