Copyright © Kevin Stone

R3C4 can only be <9>

R4C3 can only be <7>

R5C1 can only be <5>

R5C4 can only be <4>

R5C9 can only be <6>

R6C3 can only be <2>

R7C4 can only be <2>

R7C6 can only be <8>

R4C5 can only be <9>

R4C7 can only be <3>

R6C5 can only be <6>

R5C5 can only be <7>

R5C6 can only be <1>

R6C7 can only be <9>

R1C5 can only be <8>

R7C1 can only be <9>

R3C6 can only be <6>

R9C5 can only be <5>

R3C2 is the only square in row 3 that can be <7>

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

R8C8 is the only square in row 8 that can be <2>

R3C8 is the only square in column 8 that can be <3>

Squares R3C3 and R3C7 in row 3 and R9C3 and R9C7 in row 9 form a Simple X-Wing pattern on possibility <4>. All other instances of this possibility in columns 3 and 7 can be removed.

R2C3 - removing <4> from <4568> leaving <568>

R2C7 - removing <4> from <4568> leaving <568>

R7C3 - removing <4> from <1456> leaving <156>

Squares R2C3 and R2C7 in row 2 and R8C3 and R8C7 in row 8 form a Simple X-Wing pattern on possibility <8>. All other instances of this possibility in columns 3 and 7 can be removed.

R3C3 - removing <8> from <458> leaving <45>

R3C7 - removing <8> from <458> leaving <45>

R9C3 - removing <8> from <1348> leaving <134>

R9C7 - removing <8> from <148> leaving <14>

Squares R3C3 and R3C7 in row 3 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 row.

R3C9 - removing <5> from <258> leaving <28>

R7C9 is the only square in column 9 that can be <5>

R7C3 is the only square in row 7 that can be <1>

Squares R1C7 (XY), R9C7 (XZ) and R2C8 (YZ) form an XY-Wing pattern on <4>. All squares that are buddies of both the XZ and YZ squares cannot be <4>.

R7C8 - removing <4> from <46> leaving <6>

R3C7 - removing <4> from <45> leaving <5>

R3C3 can only be <4>

R7C2 can only be <4>

R2C8 can only be <4>

R8C7 can only be <8>

R2C7 can only be <6>

R9C9 can only be <1>

R9C7 can only be <4>

R1C9 can only be <2>

R1C1 can only be <3>

R3C9 can only be <8>

R1C7 can only be <1>

R2C2 can only be <5>

R9C3 can only be <3>

R3C1 can only be <2>

R9C1 can only be <8>

R1C3 can only be <6>

R8C3 can only be <5>

R2C3 can only be <8>

R8C2 can only be <6>