Puzzle Copyright © Kevin Stone

R2C9 is the only square in row 2 that can be <8>

R1C5 is the only square in row 1 that can be <8>

R1C1 is the only square in row 1 that can be <9>

R2C1 can only be <3>

R2C3 can only be <5>

R1C2 can only be <6>

R3C2 can only be <2>

R2C4 is the only square in row 2 that can be <9>

R3C8 is the only square in row 3 that can be <5>

R4C5 is the only square in row 4 that can be <1>

R5C3 is the only square in row 5 that can be <8>

R6C3 can only be <2>

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

R6C8 is the only square in row 6 that can be <8>

R7C8 is the only square in row 7 that can be <2>

R7C5 is the only square in row 7 that can be <9>

R8C4 is the only square in row 8 that can be <1>

R8C1 is the only square in row 8 that can be <2>

R5C4 is the only square in column 4 that can be <7>

R2C6 is the only square in column 6 that can be <7>

R2C7 can only be <4>

Squares R5C5 and R6C5 in column 5 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.

R3C5 - removing <4> from <346> leaving <36>

R9C5 - removing <45> from <3456> leaving <36>

Intersection of row 5 with block 6. The value <3> 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.

R4C7 - removing <3> from <367> leaving <67>

R4C8 - removing <3> from <347> leaving <47>

Intersection of column 7 with block 6. The values <67> only appears in one or more of squares R4C7, R5C7 and R6C7 of column 7. These squares are the ones that intersect with block 6. Thus, the other (non-intersecting) squares of block 6 cannot contain these values.

R4C8 - removing <7> from <47> leaving <4>

Squares R1C8, R1C9, R9C8 and R9C9 form a Type-1 Unique Rectangle on <37>.

R9C9 - removing <37> from <3457> leaving <45>

R9C8 is the only square in row 9 that can be <7>

R1C8 can only be <3>

R1C9 can only be <7>

Intersection of block 9 with row 8. The value <3> only appears in one or more of squares R8C7, R8C8 and R8C9 of block 9. These squares are the ones that intersect with row 8. Thus, the other (non-intersecting) squares of row 8 cannot contain this value.

R8C3 - removing <3> from <36> leaving <6>

R4C3 can only be <3>

R9C1 can only be <4>

R9C9 can only be <5>

R5C1 can only be <6>

R9C2 can only be <3>

R5C9 can only be <3>

R8C7 can only be <3>

R4C2 can only be <7>

R5C7 can only be <5>

R8C9 can only be <4>

R8C6 can only be <5>

R9C5 can only be <6>

R7C2 can only be <5>

R3C5 can only be <3>

R3C4 can only be <4>

R4C7 can only be <6>

R6C2 can only be <4>

R5C5 can only be <4>

R6C7 can only be <7>

R6C5 can only be <5>

R7C6 can only be <4>

R7C4 can only be <3>

R3C6 can only be <6>