Jul 20 - Very Hard
Puzzle Copyright © Kevin Stone
Share link – www.brainbashers.com
Reasoning
R1C6 can only be <6>
R4C9 can only be <1>
R5C6 can only be <7>
R6C9 can only be <9>
R9C6 can only be <3>
R6C5 can only be <2>
R5C9 can only be <8>
R5C7 can only be <6>
R6C1 can only be <7>
R4C5 can only be <4>
R4C1 can only be <2>
R7C8 is the only square in row 7 that can be <3>
R8C1 is the only square in row 8 that can be <3>
R8C2 is the only square in row 8 that can be <6>
R3C8 is the only square in row 3 that can be <6>
R2C1 is the only square in row 2 that can be <6>
R9C5 is the only square in row 9 that can be <6>
Intersection of row 2 with block 3. The value <8> only appears in one or more of squares R2C7, R2C8 and R2C9 of row 2. These squares are the ones that intersect with block 3. Thus, the other (non-intersecting) squares of block 3 cannot contain this value.
R1C8 - removing <8> from <1589> leaving <159>
Intersection of row 8 with block 9. The values <29> only appears in one or more of squares R8C7, R8C8 and R8C9 of row 8. These squares are the ones that intersect with block 9. Thus, the other (non-intersecting) squares of block 9 cannot contain these values.
R7C7 - removing <9> from <789> leaving <78>
R9C8 - removing <9> from <589> leaving <58>
Squares R1C1<19>, R1C4<58>, R1C5<158> and R1C8<159> in row 1 form a comprehensive naked quad. These 4 squares can only contain the 4 possibilities <1589>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the row.
R1C2 - removing <19> from <1279> leaving <27>
R1C9 - removing <5> from <257> leaving <27>
Squares R1C2 and R1C9 in row 1 and R9C2 and R9C9 in row 9 form a Simple X-Wing pattern on possibility <7>. All other instances of this possibility in columns 2 and 9 can be removed.
R3C2 - removing <7> from <179> leaving <19>
R7C2 - removing <7> from <179> leaving <19>
Squares R3C2 and R7C2 in column 2 form a simple naked pair. These 2 squares both contain the 2 possibilities <19>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the column.
R2C2 - removing <1> from <124> leaving <24>
R9C2 - removing <9> from <479> leaving <47>
Squares R1C1 and R3C2 in block 1 form a simple naked pair. These 2 squares both contain the 2 possibilities <19>. Since each of the squares must contain one of the possibilities, they can be eliminated from the other squares in the block.
R2C3 - removing <1> from <145> leaving <45>
R3C3 - removing <1> from <157> leaving <57>
R2C8 is the only square in row 2 that can be <1>
R2C7 is the only square in row 2 that can be <8>
R7C7 can only be <7>
R3C7 can only be <9>
R3C2 can only be <1>
R8C7 can only be <2>
R1C8 can only be <5>
R8C9 can only be <4>
R8C3 can only be <8>
R9C9 can only be <5>
R9C8 can only be <8>
R2C9 can only be <2>
R1C4 can only be <8>
R2C2 can only be <4>
R1C9 can only be <7>
R3C5 can only be <5>
R7C2 can only be <9>
R1C1 can only be <9>
R3C3 can only be <7>
R5C5 can only be <9>
R5C4 can only be <5>
R7C5 can only be <8>
R9C1 can only be <4>
R7C3 can only be <1>
R1C5 can only be <1>
R9C4 can only be <9>
R8C8 can only be <9>
R9C2 can only be <7>
R5C1 can only be <1>
R1C2 can only be <2>
R2C3 can only be <5>
R5C3 can only be <4>
Today's Sudoku Puzzles
All daily items change at midnight GMT – set your local time zone.
Note: BrainBashers has a Dark Mode setting.