Sudoku Puzzle © Kevin Stone

R2C2 is the only square in row 2 that can be <7>

R3C7 is the only square in row 3 that can be <7>

R5C5 is the only square in row 5 that can be <3>

R5C3 is the only square in row 5 that can be <7>

R6C1 can only be <2>

R5C6 is the only square in row 5 that can be <2>

R6C5 is the only square in row 6 that can be <7>

R7C1 is the only square in row 7 that can be <7>

R7C5 is the only square in block 8 that can be <1>

Squares R4C2 and R5C2 in column 2 form a simple locked pair. These 2 squares both contain the 2 possibilities <45>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the column.

R7C2 - removing <4> from <2469> leaving <269>

R8C2 - removing <4> from <3469> leaving <369>

R9C2 - removing <4> from <1349> leaving <139>

Intersection of row 2 with block 3. The value <3> only appears in one or more of squares R2C7, R2C8 and R2C9 of row 2. These squares are the ones that intersect with block 3. Thus, the other (non-intersecting) squares of block 3 cannot contain this value.

R1C8 - removing <3> from <12368> leaving <1268>

R1C9 - removing <3> from <368> leaving <68>

R2C9 is the only square in column 9 that can be <3>

Squares R1C7 and R1C9 in row 1 form a simple locked pair. These 2 squares both contain the 2 possibilities <68>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the row.

R1C2 - removing <6> from <12369> leaving <1239>

R1C6 - removing <8> from <189> leaving <19>

R1C8 - removing <68> from <1268> leaving <12>

Squares R1C7 and R1C9 in block 3 form a simple locked pair. These 2 squares both contain the 2 possibilities <68>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the block.

R2C8 - removing <6> from <156> leaving <15>

R3C8 - removing <68> from <124568> leaving <1245>

R3C9 - removing <68> from <4568> leaving <45>

R2C5 is the only square in row 2 that can be <6>

Intersection of column 4 with block 8. The values <49> only appears in one or more of squares R7C4, R8C4 and R9C4 of column 4. These squares are the ones that intersect with block 8. Thus, the other (non-intersecting) squares of block 8 cannot contain these values.

R8C5 - removing <9> from <89> leaving <8>

R8C1 can only be <6>

R3C1 can only be <1>

R9C1 can only be <8>

R3C2 is the only square in row 3 that can be <6>

R3C6 is the only square in row 3 that can be <8>

R4C9 is the only square in row 4 that can be <8>

R1C9 can only be <6>

R1C7 can only be <8>

R4C2 is the only square in row 4 that can be <4>

R5C2 can only be <5>

R5C4 is the only square in row 5 that can be <8>

R7C8 is the only square in row 7 that can be <8>

R7C7 is the only square in row 7 that can be <6>

R5C7 can only be <4>

R5C8 can only be <6>

R9C7 can only be <5>

R6C8 can only be <5>

R6C4 can only be <6>

R2C8 can only be <1>

R7C9 can only be <4>

R2C6 can only be <5>

R1C8 can only be <2>

R3C9 can only be <5>

R3C8 can only be <4>

R4C6 can only be <9>

R3C5 can only be <9>

R3C3 can only be <2>

R4C5 can only be <5>

R1C6 can only be <1>

R7C3 can only be <9>

R7C2 can only be <2>

R7C4 can only be <5>

R1C3 can only be <3>

R8C2 can only be <3>

R8C8 can only be <9>

R1C2 can only be <9>

R9C2 can only be <1>

R9C3 can only be <4>

R8C4 can only be <4>

R9C8 can only be <3>

R9C4 can only be <9>