     Sudoku Solution Path   Copyright © Kevin Stone R1C7 can only be <4> R8C1 can only be <4> R3C7 can only be <8> R6C7 can only be <3> R9C7 can only be <1> R1C4 is the only square in row 1 that can be <1> R2C3 is the only square in row 2 that can be <8> R3C2 is the only square in row 3 that can be <4> R4C2 is the only square in row 4 that can be <1> R5C8 is the only square in row 5 that can be <1> R6C5 is the only square in row 6 that can be <9> R6C4 is the only square in row 6 that can be <2> R8C3 is the only square in row 8 that can be <1> R1C2 is the only square in column 2 that can be <2> R5C2 is the only square in block 4 that can be <3> R5C9 is the only square in row 5 that can be <6> Squares R3C3 and R3C9 in row 3 form a simple locked pair. These 2 squares both contain the 2 possibilities <57>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the row.    R3C5 - removing <57> from <23567> leaving <236>    R3C6 - removing <57> from <2357> leaving <23>    R3C8 - removing <57> from <567> leaving <6> Squares R7C1 and R9C1 in column 1 form a simple locked pair. These 2 squares both contain the 2 possibilities <25>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the column.    R5C1 - removing <5> from <578> leaving <78>    R6C1 - removing <5> from <578> leaving <78> Squares R5C1 and R6C1 in block 4 form a simple locked pair. These 2 squares both contain the 2 possibilities <78>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the block.    R6C3 - removing <7> from <567> leaving <56> R6C1 is the only square in row 6 that can be <7> R5C1 can only be <8> R6C8 is the only square in row 6 that can be <8> R4C9 can only be <5> R4C5 can only be <3> R3C9 can only be <7> R3C3 can only be <5> R1C9 can only be <9> R4C4 can only be <8> R3C5 can only be <2> R9C9 can only be <3> R2C8 can only be <5> R2C2 can only be <9> R1C3 can only be <7> R6C3 can only be <6> R3C6 can only be <3> R6C2 can only be <5> R9C3 can only be <9> R7C9 can only be <8> R1C6 can only be <5> R5C6 can only be <7> R8C2 can only be <6> R8C5 can only be <7> R8C4 can only be <3> R8C8 can only be <9> R2C5 can only be <6> R8C6 can only be <8> R7C8 can only be <4> R9C6 can only be <2> R7C3 can only be <3> R9C1 can only be <5> R7C6 can only be <9> R2C4 can only be <7> R7C4 can only be <5> R9C8 can only be <7> R9C5 can only be <4> R7C1 can only be <2> R9C4 can only be <6> R5C5 can only be <5> R5C4 can only be <4> [Puzzle Code = Sudoku-20190822-Hard-312648]    