Step-by-Step Solution

for Friday 14th March Diabolical

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

Single Candidate

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

Single Position

For column 6, Number 8 is only possible in cell (6,1)

Single Position

For box 5, Number 7 is only possible in cell (6,6)

Single Position

Number 1 is the only value possible in cell (6,8).

Single Candidate

For row 5, number 4 is only possible in cell (3,5)

Single Position

For column 8, Number 4 is only possible in cell (8,9)

Single Position

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

Single Position

For row 7, number 5 is only possible in cell (6,7)

Single Position

For row 6, number 1 is only possible in cell (7,6)

Single Position

For box 6, candidates for 2 are all in row 4, so you can remove candidates from other blocks.

Candidate Lines

Candidates for 3 in boxes 5 and 6 force the candidates in box 4 to be in the remaining line.

Multiple Lines

Naked Pair for 3 and 9, can remove these as candidates from other cells.

Naked Pairs

Naked Pair for 2 and 6, can remove these as candidates from other cells.

Naked Pairs

Hidden Pair for 4 and 9, can remove other candidates from these cells.

Hidden Pairs

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

Candidate Lines

X-Wing in rows for 3.

X-Wings

For box 6, candidates for 3 are all in column 8, so you can remove candidates from other blocks.

Candidate Lines

Either candidate for cell (3,4) forces 9 into cell (3,8).

Forcing Chains

Number 2 is the only value possible in cell (3,6).

Single Candidate

Number 4 is the only value possible in cell (5,8).

Single Candidate

Number 9 is the only value possible in cell (5,3).

Single Candidate

Number 7 is the only value possible in cell (4,8).

Single Candidate

Number 3 is the only value possible in cell (7,8).

Single Candidate

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

Single Candidate

Number 9 is the only value possible in cell (1,6).

Single Candidate

Number 3 is the only value possible in cell (2,6).

Single Candidate

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

Single Candidate

For row 1, number 9 is only possible in cell (2,1)

Single Position

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

Single Position

For row 1, number 3 is only possible in cell (9,1)

Single Position

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

Single Position

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

Multiple Lines

Either candidate for cell (3,1) forces 3 into cell (8,4).

Forcing Chains

For row 4, number 2 is only possible in cell (7,4)

Single Position

For row 4, number 8 is only possible in cell (3,4)

Single Position

Number 6 is the only value possible in cell (2,5).

Single Candidate

Number 1 is the only value possible in cell (2,3).

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

Number 5 is the only value possible in cell (1,3).

Single Candidate

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

Single Candidate

Number 1 is the only value possible in cell (3,7).

Single Candidate

Number 7 is the only value possible in cell (2,9).

Single Candidate

Number 8 is the only value possible in cell (2,7).

Single Candidate

Number 6 is the only value possible in cell (7,9).

Single Candidate

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

Single Candidate

Number 8 is the only value possible in cell (7,3).

Single Candidate

Number 2 is the only value possible in cell (8,3).

Single Candidate

Number 6 is the only value possible in cell (9,3).

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

Number 2 is the only value possible in cell (9,7).

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

Number 1 is the only value possible in cell (4,2).

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate