Dec 11 - Super Hard
Puzzle Copyright © Kevin Stone
Share link – www.brainbashers.com
Reasoning
R6C8 can only be <7>
R1C7 is the only square in row 1 that can be <1>
R2C2 is the only square in row 2 that can be <2>
R7C7 is the only square in row 7 that can be <2>
R8C2 is the only square in row 8 that can be <7>
R1C3 is the only square in column 3 that can be <5>
Squares R6C2 and R6C5 in row 6 and R9C2 and R9C5 in row 9 form a Simple X-Wing pattern on possibility <1>. All other instances of this possibility in columns 2 and 5 can be removed.
R5C2 - removing <1> from <1589> leaving <589>
R5C5 - removing <1> from <12569> leaving <2569>
R8C5 - removing <1> from <1346> leaving <346>
Squares R1C5 and R1C8 in row 1 and R9C5 and R9C8 in row 9 form a Simple X-Wing pattern on possibility <3>. All other instances of this possibility in columns 5 and 8 can be removed.
R2C5 - removing <3> from <3459> leaving <459>
R2C8 - removing <3> from <34689> leaving <4689>
R8C5 - removing <3> from <346> leaving <46>
R8C8 - removing <3> from <34689> leaving <4689>
Squares R8C5 and R8C6 in row 8 form a simple naked pair. These 2 squares both contain the 2 possibilities <46>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the row.
R8C1 - removing <4> from <1489> leaving <189>
R8C8 - removing <46> from <4689> leaving <89>
R8C9 - removing <46> from <34689> leaving <389>
Squares R8C5 and R8C6 in block 8 form a simple naked pair. These 2 squares both contain the 2 possibilities <46>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the block.
R9C5 - removing <46> from <1346> leaving <13>
Squares R3C3 and R9C3 in column 3 and R3C7 and R9C7 in column 7 form a Simple X-Wing pattern on possibility <8>. All other instances of this possibility in rows 3 and 9 can be removed.
R3C1 - removing <8> from <3489> leaving <349>
R9C2 - removing <8> from <148> leaving <14>
R9C8 - removing <8> from <3468> leaving <346>
R3C9 - removing <8> from <3489> leaving <349>
Intersection of column 2 with block 4. The values <58> only appears in one or more of squares R4C2, R5C2 and R6C2 of column 2. These squares are the ones that intersect with block 4. Thus, the other (non-intersecting) squares of block 4 cannot contain these values.
R5C1 - removing <8> from <189> leaving <19>
Squares R5C1 and R6C2 in block 4 form a simple naked pair. These 2 squares both contain the 2 possibilities <19>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the block.
R5C2 - removing <9> from <589> leaving <58>
Squares R3C3 (XY), R3C7 (XZ) and R1C2 (YZ) form an XY-Wing pattern on <4>. All squares that are buddies of both the XZ and YZ squares cannot be <4>.
R1C8 - removing <4> from <349> leaving <39>
R3C1 - removing <4> from <349> leaving <39>
Intersection of row 3 with block 3. The value <4> only appears in one or more of squares R3C7, R3C8 and R3C9 of row 3. These squares are the ones that intersect with block 3. Thus, the other (non-intersecting) squares of block 3 cannot contain this value.
R2C8 - removing <4> from <4689> leaving <689>
R2C9 - removing <4> from <34689> leaving <3689>
Squares R7C1 (XY), R9C2 (XZ) and R5C1 (YZ) form an XY-Wing pattern on <1>. All squares that are buddies of both the XZ and YZ squares cannot be <1>.
R8C1 - removing <1> from <189> leaving <89>
R6C2 - removing <1> from <19> leaving <9>
R6C5 can only be <1>
R1C2 can only be <4>
R5C1 can only be <1>
R9C5 can only be <3>
R5C4 can only be <5>
R8C4 can only be <1>
R1C5 can only be <9>
R9C2 can only be <1>
R1C8 can only be <3>
R2C6 can only be <4>
R2C5 can only be <5>
R8C6 can only be <6>
R5C2 can only be <8>
R2C4 can only be <3>
R4C5 can only be <2>
R8C5 can only be <4>
R5C6 can only be <9>
R4C8 can only be <8>
R5C5 can only be <6>
R4C2 can only be <5>
R8C8 can only be <9>
R5C9 can only be <4>
R5C8 can only be <2>
R3C9 can only be <9>
R8C1 can only be <8>
R2C8 can only be <6>
R7C9 can only be <6>
R9C8 can only be <4>
R3C1 can only be <3>
R3C3 can only be <8>
R2C9 can only be <8>
R7C3 can only be <9>
R8C9 can only be <3>
R2C1 can only be <9>
R9C3 can only be <6>
R9C7 can only be <8>
R7C1 can only be <4>
R3C7 can only be <4>
Today's Sudoku Puzzles
All daily items change at midnight GMT – set your local time zone.
Note: BrainBashers has a Dark Mode setting.