The full reasoning can be found below the Sudoku.
Jan 12 - Super Hard
Puzzle Copyright © Kevin Stone
Share link: https://www.brainbashers.com/
Reasoning
R5C7 can only be <5>
R4C9 can only be <7>
R2C6 is the only square in row 2 that can be <8>
R5C2 is the only square in row 5 that can be <8>
R5C4 is the only square in row 5 that can be <9>
R5C6 is the only square in row 5 that can be <1>
R5C3 is the only square in row 5 that can be <4>
R4C2 can only be <3>
R4C5 can only be <5>
R6C1 can only be <5>
R4C6 can only be <4>
R3C6 is the only square in row 3 that can be <3>
R6C5 is the only square in row 6 that can be <7>
R9C2 is the only square in column 2 that can be <2>
R1C2 is the only square in column 2 that can be <4>
R3C2 is the only square in column 2 that can be <9>
R3C7 can only be <6>
R1C4 is the only square in column 4 that can be <1>
Squares R1C1 and R7C1 in column 1 form a simple naked pair. These 2 squares both contain the 2 possibilities <36>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the column.
R8C1 - removing <6> from <469> leaving <49>
R9C1 - removing <36> from <3469> leaving <49>
Squares R5C8 and R6C8 in column 8 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.
R1C8 - removing <2> from <2578> leaving <578>
Squares R3C8 and R3C9 in block 3 form a simple naked pair. These 2 squares both contain the 2 possibilities <15>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the block.
R1C8 - removing <5> from <578> leaving <78>
R1C9 - removing <5> from <259> leaving <29>
R2C9 - removing <5> from <25> leaving <2>
R1C9 can only be <9>
Squares R1C7 and R1C8 in row 1 form a simple naked pair. These 2 squares both contain the 2 possibilities <78>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the row.
R1C3 - removing <7> from <357> leaving <35>
Intersection of block 7 with row 7. The value <6> only appears in one or more of squares R7C1, R7C2 and R7C3 of block 7. These squares are the ones that intersect with row 7. Thus, the other (non-intersecting) squares of row 7 cannot contain this value.
R7C4 - removing <6> from <356> leaving <35>
R7C8 - removing <6> from <1567> leaving <157>
Squares R1C7, R1C8, R9C7 and R9C8 form a Type-4 Unique Rectangle on <78>.
R9C7 - removing <7> from <789> leaving <89>
R9C8 - removing <7> from <15678> leaving <1568>
Squares R3C8, R3C9, R9C8 and R9C9 form a Type-1 Unique Rectangle on <15>.
R9C8 - removing <15> from <1568> leaving <68>
Squares R1C8<78>, R8C8<67> and R9C8<68> in column 8 form a comprehensive naked triplet. These 3 squares can only contain the 3 possibilities <678>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the column.
R7C8 - removing <7> from <157> leaving <15>
Intersection of row 7 with block 7. The values <67> only appears in one or more of squares R7C1, R7C2 and R7C3 of row 7. These squares are the ones that intersect with block 7. Thus, the other (non-intersecting) squares of block 7 cannot contain these values.
R9C3 - removing <7> from <137> leaving <13>
R9C6 is the only square in row 9 that can be <7>
R8C6 can only be <2>
R1C6 can only be <5>
R1C3 can only be <3>
R2C4 can only be <6>
R2C2 can only be <7>
R8C4 can only be <4>
R1C5 can only be <2>
R8C1 can only be <9>
R1C1 can only be <6>
R9C3 can only be <1>
R5C5 can only be <3>
R2C3 can only be <5>
R7C2 can only be <6>
R5C8 can only be <2>
R9C5 can only be <6>
R6C4 can only be <2>
R6C8 can only be <3>
R7C1 can only be <3>
R8C7 can only be <7>
R9C1 can only be <4>
R8C8 can only be <6>
R1C7 can only be <8>
R9C8 can only be <8>
R9C9 can only be <5>
R7C3 can only be <7>
R9C7 can only be <9>
R1C8 can only be <7>
R9C4 can only be <3>
R3C9 can only be <1>
R7C8 can only be <1>
R3C8 can only be <5>
R7C4 can only be <5>
Today's Sudoku Puzzles
All daily items change at midnight GMT set time zone