Copyright © Kevin Stone

R5C1 can only be <3>

R2C7 is the only square in row 2 that can be <8>

R3C3 is the only square in row 3 that can be <2>

R3C2 is the only square in row 3 that can be <1>

R5C2 can only be <9>

R5C8 can only be <7>

R4C3 can only be <7>

R5C6 can only be <5>

R5C9 can only be <8>

R6C3 can only be <1>

R5C5 can only be <6>

R5C4 can only be <1>

R3C4 is the only square in row 3 that can be <6>

R4C5 is the only square in row 4 that can be <2>

R4C6 is the only square in row 4 that can be <4>

R6C4 is the only square in row 6 that can be <8>

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

R7C3 is the only square in row 7 that can be <8>

R9C7 is the only square in row 9 that can be <1>

R8C3 is the only square in column 3 that can be <9>

R2C3 is the only square in column 3 that can be <6>

Squares R4C7 and R6C7 in column 7 form a simple locked pair. These 2 squares both contain the 2 possibilities <39>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the column.

R1C7 - removing <3> from <345> leaving <45>

R3C7 - removing <39> from <34579> leaving <457>

R7C7 - removing <3> from <3567> leaving <567>

R8C7 - removing <3> from <3567> leaving <567>

Squares R7C4<39>, R7C6<379> and R7C9<37> in row 7 form a comprehensive locked triplet. These 3 squares can only contain the 3 possibilities <379>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the row.

R7C2 - removing <3> from <346> leaving <46>

R7C7 - removing <7> from <567> leaving <56>

Squares R1C3 and R1C5 in row 1 and R9C3 and R9C5 in row 9 form a Simple X-Wing pattern on possibility <3>. All other instances of this possibility in columns 3 and 5 can be removed.

R2C5 - removing <3> from <349> leaving <49>

R6C5 - removing <3> from <379> leaving <79>

R8C5 - removing <3> from <357> leaving <57>

Squares R2C2 and R2C8 in row 2 and R8C2 and R8C8 in row 8 form a Simple X-Wing pattern on possibility <3>. All other instances of this possibility in columns 2 and 8 can be removed.

R3C8 - removing <3> from <359> leaving <59>

Squares R8C8 (XY), R8C2 (XZ) and R7C7 (YZ) form an XY-Wing pattern on <6>. All squares that are buddies of both the XZ and YZ squares cannot be <6>.

R7C2 - removing <6> from <46> leaving <4>

R8C7 - removing <6> from <567> leaving <57>

R7C1 can only be <5>

R2C2 can only be <3>

R2C8 can only be <9>

R8C2 can only be <6>

R1C3 can only be <5>

R2C5 can only be <4>

R3C8 can only be <5>

R3C1 can only be <4>

R8C8 can only be <3>

R1C7 can only be <4>

R7C7 can only be <6>

R9C3 can only be <3>

R7C9 can only be <7>

R9C5 can only be <5>

R8C5 can only be <7>

R1C5 can only be <3>

R3C7 can only be <7>

R3C9 can only be <3>

R8C7 can only be <5>

R3C6 can only be <9>

R6C5 can only be <9>

R7C6 can only be <3>

R6C7 can only be <3>

R4C4 can only be <3>

R6C6 can only be <7>

R4C7 can only be <9>

R7C4 can only be <9>