Puzzle Copyright © Kevin Stone

R4C4 can only be <2>

R4C8 can only be <1>

R5C2 can only be <3>

R6C4 can only be <6>

R6C6 can only be <3>

R7C5 can only be <5>

R8C6 can only be <7>

R4C6 can only be <9>

R2C4 can only be <7>

R4C2 can only be <7>

R5C3 can only be <9>

R6C2 can only be <1>

R3C2 can only be <5>

R6C8 can only be <8>

R5C5 can only be <8>

R5C7 can only be <4>

R7C9 can only be <4>

R8C5 can only be <6>

R3C9 can only be <1>

R8C4 can only be <4>

R2C6 can only be <2>

R7C2 can only be <2>

R5C8 can only be <6>

R1C9 is the only square in row 1 that can be <2>

R2C1 is the only square in row 2 that can be <1>

R3C8 is the only square in row 3 that can be <4>

R8C7 is the only square in row 8 that can be <1>

R9C1 is the only square in row 9 that can be <4>

R2C9 is the only square in column 9 that can be <6>

R2C3 can only be <3>

R2C5 can only be <9>

R8C3 can only be <5>

R3C1 can only be <9>

R2C7 can only be <8>

R3C5 can only be <3>

R9C7 can only be <9>

R8C9 can only be <8>

R8C1 can only be <3>

R9C9 can only be <5>

R9C8 can only be <7>

R1C7 can only be <3>

R9C3 can only be <6>

R7C8 can only be <3>

R1C8 can only be <9>

R7C1 can only be <7>

R9C2 can only be <8>

R1C3 can only be <7>

R1C1 can only be <8>

R1C2 can only be <6>