The full reasoning can be found below the Sudoku.
Apr 16 - Very Hard
Puzzle Copyright © Kevin Stone
Share link:
Reasoning
R7C9 can only be <8>
R7C2 can only be <9>
R7C1 can only be <7>
R7C8 can only be <1>
R1C3 is the only square in row 1 that can be <9>
R3C2 is the only square in row 3 that can be <1>
R4C4 is the only square in row 4 that can be <7>
R4C9 is the only square in row 4 that can be <5>
R6C9 can only be <4>
R6C1 can only be <9>
R6C6 can only be <8>
R5C8 can only be <8>
R6C5 can only be <3>
R6C4 can only be <5>
R9C6 can only be <6>
R9C4 can only be <8>
R8C5 can only be <1>
R2C7 is the only square in row 2 that can be <8>
R2C8 is the only square in row 2 that can be <7>
R4C6 is the only square in row 4 that can be <1>
R5C5 is the only square in row 5 that can be <9>
R8C2 is the only square in row 8 that can be <8>
R9C7 is the only square in row 9 that can be <7>
Intersection of row 2 with block 1. The value <5> only appears in one or more of squares R2C1, R2C2 and R2C3 of row 2. These squares are the ones that intersect with block 1. Thus, the other (non-intersecting) squares of block 1 cannot contain this value.
R1C2 - removing <5> from <3456> leaving <346>
Intersection of block 2 with row 1. The value <2> only appears in one or more of squares R1C4, R1C5 and R1C6 of block 2. These squares are the ones that intersect with row 1. Thus, the other (non-intersecting) squares of row 1 cannot contain this value.
R1C8 - removing <2> from <2345> leaving <345>
Squares R1C2 and R1C8 in row 1 and R9C2 and R9C8 in row 9 form a Simple X-Wing pattern on possibility <3>. All other instances of this possibility in columns 2 and 8 can be removed.
R2C2 - removing <3> from <3456> leaving <456>
R8C8 - removing <3> from <2345> leaving <245>
Squares R2C2<456>, R2C3<456> and R2C5<46> in row 2 form a comprehensive naked triplet. These 3 squares can only contain the 3 possibilities <456>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the row.
R2C1 - removing <46> from <2346> leaving <23>
R2C9 - removing <6> from <236> leaving <23>
R3C9 is the only square in column 9 that can be <6>
Squares R1C2 and R1C4 in row 1 and R5C2 and R5C4 in row 5 form a Simple X-Wing pattern on possibility <6>. All other instances of this possibility in columns 2 and 4 can be removed.
R2C2 - removing <6> from <456> leaving <45>
Squares R2C5 and R5C2 form a remote naked pair. <46> can be removed from any square that is common to their groups.
R2C2 - removing <4> from <45> leaving <5>
Squares R2C3 and R4C1 form a remote naked pair. <46> can be removed from any square that is common to their groups.
R3C1 - removing <4> from <24> leaving <2>
R3C8 can only be <4>
R2C1 can only be <3>
R1C7 can only be <5>
R1C8 can only be <3>
R8C7 can only be <4>
R9C8 can only be <5>
R2C9 can only be <2>
R8C9 can only be <3>
R8C1 can only be <6>
R9C3 can only be <4>
R8C8 can only be <2>
R8C3 can only be <5>
R4C1 can only be <4>
R9C2 can only be <3>
R2C3 can only be <6>
R2C5 can only be <4>
R1C2 can only be <4>
R4C5 can only be <6>
R1C6 can only be <2>
R5C2 can only be <6>
R5C4 can only be <2>
R5C6 can only be <4>
R1C4 can only be <6>
Today's Sudoku Puzzles
All daily items change at midnight GMT – set your local time zone.
Note: BrainBashers has a Dark Mode option – I recommend not using your browser's dark mode or extensions for BrainBashers