Step-by-Step Solution

for Friday 13th March Diabolical

For column 8, Number 8 is only possible in cell (8,8)

Single Position

For column 9, Number 7 is only possible in cell (9,1)

Single Position

For column 1, Number 7 is only possible in cell (1,3)

Single Position

For row 3, number 4 is only possible in cell (2,3)

Single Position

For row 8, number 3 is only possible in cell (6,8)

Single Position

For box 4, Number 1 is only possible in cell (3,5)

Single Position

For row 9, number 3 is only possible in cell (7,9)

Single Position

For row 9, number 6 is only possible in cell (2,9)

Single Position

For row 9, number 8 is only possible in cell (3,9)

Single Position

For row 1, number 8 is only possible in cell (6,1)

Single Position

For row 2, number 8 is only possible in cell (2,2)

Single Position

For row 4, number 8 is only possible in cell (4,4)

Single Position

For row 4, number 3 is only possible in cell (2,4)

Single Position

For row 6, number 3 is only possible in cell (4,6)

Single Position

For row 6, number 2 is only possible in cell (8,6)

Single Position

For row 5, number 2 is only possible in cell (4,5)

Single Position

For column 4, Number 7 is only possible in cell (4,9)

Single Position

For box 6, Number 4 is only possible in cell (8,5)

Single Position

For column 8, Number 7 is only possible in cell (8,4)

Single Position

For box 1, candidates for 2 are all in column 1, so you can remove candidates from other blocks.

Candidate Lines

For box 6, candidates for 9 are all in column 7, so you can remove candidates from other blocks.

Candidate Lines

For box 8, candidates for 5 are all in row 7, so you can remove candidates from other blocks.

Candidate Lines

Either candidate for cell (4,3) forces 3 into cell (3,3).

Forcing Chains

For row 1, number 3 is only possible in cell (8,1)

Single Position

Candidates for 9 in boxes 2 and 3 force the candidates in box 1 to be in the remaining line.

Multiple Lines

Either candidate for cell (2,7) forces 2 into cell (1,2).

Forcing Chains

For row 1, number 2 is only possible in cell (7,1)

Single Position

Number 6 is the only value possible in cell (7,7).

Single Candidate

For row 1, number 6 is only possible in cell (5,1)

Single Position

For row 3, number 6 is only possible in cell (8,3)

Single Position

For row 5, number 6 is only possible in cell (6,5)

Single Position

For row 2, number 5 is only possible in cell (4,2)

Single Position

Number 1 is the only value possible in cell (4,7).

Single Candidate

Number 9 is the only value possible in cell (4,3).

Single Candidate

Number 1 is the only value possible in cell (6,3).

Single Candidate

Number 9 is the only value possible in cell (8,7).

Single Candidate

Number 1 is the only value possible in cell (8,2).

Single Candidate

Number 9 is the only value possible in cell (9,2).

Single Candidate

Number 2 is the only value possible in cell (2,7).

Single Candidate

Number 4 is the only value possible in cell (9,7).

Single Candidate

Number 5 is the only value possible in cell (6,7).

Single Candidate

Number 9 is the only value possible in cell (6,4).

Single Candidate

Number 5 is the only value possible in cell (7,4).

Single Candidate

Number 1 is the only value possible in cell (5,4).

Single Candidate

Number 9 is the only value possible in cell (7,5).

Single Candidate

Number 4 is the only value possible in cell (6,6).

Single Candidate

Number 5 is the only value possible in cell (2,8).

Single Candidate

Number 7 is the only value possible in cell (2,5).

Single Candidate

Number 5 is the only value possible in cell (5,5).

Single Candidate

Number 9 is the only value possible in cell (2,6).

Single Candidate

Number 5 is the only value possible in cell (3,6).

Single Candidate

Number 9 is the only value possible in cell (3,1).

Single Candidate

Number 5 is the only value possible in cell (1,1).

Single Candidate

Number 7 is the only value possible in cell (5,6).

Single Candidate

Number 1 is the only value possible in cell (1,8).

Single Candidate

Number 2 is the only value possible in cell (9,8).

Single Candidate

Number 9 is the only value possible in cell (1,9).

Single Candidate

Number 4 is the only value possible in cell (5,9).

Single Candidate

Number 1 is the only value possible in cell (9,9).

Single Candidate