The full reasoning can be found below the Sudoku.
Apr 11 - Super Hard
Puzzle Copyright © Kevin Stone
Share link:
Reasoning
R1C5 is the only square in row 1 that can be <9>
R1C2 is the only square in row 1 that can be <4>
R2C8 is the only square in row 2 that can be <3>
R4C3 is the only square in row 4 that can be <3>
R4C8 is the only square in row 4 that can be <9>
R8C2 is the only square in row 8 that can be <8>
R9C5 is the only square in row 9 that can be <3>
R9C8 is the only square in row 9 that can be <4>
R6C3 is the only square in column 3 that can be <6>
Intersection of row 5 with block 6. The value <8> only appears in one or more of squares R5C7, R5C8 and R5C9 of row 5. These squares are the ones that intersect with block 6. Thus, the other (non-intersecting) squares of block 6 cannot contain this value.
R6C8 - removing <8> from <58> leaving <5>
Intersection of row 9 with block 7. The value <6> only appears in one or more of squares R9C1, R9C2 and R9C3 of row 9. These squares are the ones that intersect with block 7. Thus, the other (non-intersecting) squares of block 7 cannot contain this value.
R8C1 - removing <6> from <2567> leaving <257>
Squares R5C5 and R8C5 in column 5 and R5C9 and R8C9 in column 9 form a Simple X-Wing pattern on possibility <1>. All other instances of this possibility in rows 5 and 8 can be removed.
R5C1 - removing <1> from <1257> leaving <257>
R5C2 - removing <1> from <1257> leaving <257>
R8C6 - removing <1> from <12456> leaving <2456>
R2C1 is the only square in column 1 that can be <1>
Squares R1C1 and R1C8 in row 1 and R8C1 and R8C8 in row 8 form a Simple X-Wing pattern on possibility <7>. All other instances of this possibility in columns 1 and 8 can be removed.
R5C1 - removing <7> from <257> leaving <25>
Intersection of block 4 with column 2. The values <17> only appears in one or more of squares R4C2, R5C2 and R6C2 of block 4. These squares are the ones that intersect with column 2. Thus, the other (non-intersecting) squares of column 2 cannot contain these values.
R2C2 - removing <7> from <567> leaving <56>
Intersection of row 2 with block 2. The values <47> only appears in one or more of squares R2C4, R2C5 and R2C6 of row 2. These squares are the ones that intersect with block 2. Thus, the other (non-intersecting) squares of block 2 cannot contain these values.
R3C4 - removing <7> from <2578> leaving <258>
Squares R1C8 (XY), R3C7 (XZ) and R5C8 (YZ) form an XY-Wing pattern on <2>. All squares that are buddies of both the XZ and YZ squares cannot be <2>.
R4C7 - removing <2> from <124> leaving <14>
R4C2 is the only square in row 4 that can be <2>
R5C1 can only be <5>
R5C2 can only be <7>
R5C5 can only be <1>
R6C2 can only be <1>
R8C5 can only be <4>
R6C7 can only be <4>
R6C6 can only be <8>
R4C7 can only be <1>
R2C5 can only be <7>
R6C4 can only be <7>
R3C4 is the only square in row 3 that can be <8>
R7C6 is the only square in row 7 that can be <1>
R8C9 is the only square in row 8 that can be <1>
R9C9 is the only square in column 9 that can be <5>
R9C2 can only be <6>
R9C1 can only be <2>
R2C2 can only be <5>
R3C3 can only be <7>
R3C7 can only be <2>
R7C3 can only be <5>
R1C1 can only be <6>
R3C6 can only be <5>
R7C7 can only be <7>
R2C9 can only be <6>
R7C4 can only be <2>
R2C4 can only be <4>
R8C8 can only be <2>
R8C1 can only be <7>
R5C8 can only be <8>
R1C9 can only be <8>
R1C8 can only be <7>
R5C9 can only be <2>
R2C6 can only be <2>
R4C4 can only be <6>
R8C6 can only be <6>
R4C6 can only be <4>
R8C4 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