Feb 08 - Super Hard
Puzzle Copyright © Kevin Stone
Share link:
Reasoning
R2C6 can only be <6>
R4C3 is the only square in row 4 that can be <7>
R9C5 is the only square in row 9 that can be <7>
R8C8 is the only square in row 8 that can be <7>
R7C5 is the only square in column 5 that can be <8>
R7C8 can only be <2>
R7C7 can only be <5>
R7C3 can only be <1>
R7C2 can only be <9>
R1C3 can only be <6>
R9C1 can only be <5>
R3C3 can only be <5>
R3C8 is the only square in row 3 that can be <6>
R5C2 is the only square in row 5 that can be <2>
R8C2 can only be <4>
R6C3 can only be <4>
R9C3 can only be <2>
R9C4 can only be <1>
R9C6 can only be <4>
R1C5 is the only square in row 1 that can be <4>
R4C8 is the only square in row 4 that can be <4>
Squares R4C5 and R6C5 in column 5 form a simple naked pair. These 2 squares both contain the 2 possibilities <23>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the column.
R2C5 - removing <3> from <135> leaving <15>
R3C5 - removing <3> from <139> leaving <19>
R8C5 - removing <2> from <259> leaving <59>
Squares R1C9<389>, R5C9<89> and R9C9<38> in column 9 form a comprehensive naked triplet. These 3 squares can only contain the 3 possibilities <389>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the column.
R4C9 - removing <38> from <3568> leaving <56>
R6C9 - removing <39> from <3569> leaving <56>
Squares R4C1<68>, R4C2<58> and R4C9<56> in row 4 form a comprehensive naked triplet. These 3 squares can only contain the 3 possibilities <568>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the row.
R4C7 - removing <8> from <238> leaving <23>
Intersection of row 4 with block 4. The value <8> only appears in one or more of squares R4C1, R4C2 and R4C3 of row 4. These squares are the ones that intersect with block 4. Thus, the other (non-intersecting) squares of block 4 cannot contain this value.
R5C1 - removing <8> from <189> leaving <19>
Squares R4C5, R4C7, R6C5 and R6C7 form a Type-1 Unique Rectangle on <23>.
R6C7 - removing <23> from <1239> leaving <19>
R6C5 is the only square in row 6 that can be <2>
R4C5 can only be <3>
R4C7 can only be <2>
R6C8 is the only square in row 6 that can be <3>
Squares R5C1 (XY), R1C1 (XZ) and R5C9 (YZ) form an XY-Wing pattern on <8>. All squares that are buddies of both the XZ and YZ squares cannot be <8>.
R1C9 - removing <8> from <389> leaving <39>
Squares R1C4<23>, R1C6<29> and R1C9<39> in row 1 form a comprehensive naked triplet. These 3 squares can only contain the 3 possibilities <239>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the row.
R1C7 - removing <39> from <1389> leaving <18>
Squares R1C7 and R2C8 in block 3 form a simple naked pair. These 2 squares both contain the 2 possibilities <18>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the block.
R3C7 - removing <1> from <139> leaving <39>
Squares R1C1 and R5C8 form a remote naked pair. <18> can be removed from any square that is common to their groups.
R5C1 - removing <1> from <19> leaving <9>
R5C9 can only be <8>
R5C8 can only be <1>
R9C9 can only be <3>
R9C7 can only be <8>
R1C9 can only be <9>
R1C6 can only be <2>
R3C7 can only be <3>
R3C2 can only be <1>
R2C8 can only be <8>
R6C7 can only be <9>
R1C7 can only be <1>
R1C4 can only be <3>
R8C6 can only be <9>
R1C1 can only be <8>
R3C5 can only be <9>
R2C2 can only be <3>
R6C2 can only be <5>
R8C5 can only be <5>
R6C9 can only be <6>
R4C2 can only be <8>
R6C1 can only be <1>
R4C9 can only be <5>
R8C4 can only be <2>
R2C5 can only be <1>
R4C1 can only be <6>
R2C4 can only be <5>
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