Step-by-Step Solution

for Monday 20th January Diabolical

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

Single Candidate

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

Single Position

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

Single Position

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

Single Position

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

Single Position

For row 9, number 4 is only possible in cell (6,9)

Single Position

For box 2, candidates for 2 are all in column 5, so you can remove candidates from other blocks.

Candidate Lines

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

Candidate Lines

For box 2, candidates for 5 are all in column 4, so you can remove candidates from other blocks.

Candidate Lines

For box 9, candidates for 5 are all in row 8, so you can remove candidates from other blocks.

Candidate Lines

For box 6, candidates for 1 are all in column 8, so you can remove candidates from other blocks.

Candidate Lines

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

Multiple Lines

For column 7, Number 2 is only possible in cell (7,6)

Single Position

For row 4, number 2 is only possible in cell (6,4)

Single Position

For blocks 4 and 6, candidates for 8 are all in the same two rows (4 and 5)

Double Pairs

Hidden Pair for 8 and 9, can remove other candidates from these cells.

Hidden Pairs

For row 4, number 6 is only possible in cell (5,4)

Single Position

For column 5, Number 9 is only possible in cell (5,6)

Single Position

Candidates for 5 in boxes 4 and 7 force the candidates in box 1 to be in the remaining line.

Multiple Lines

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

Single Candidate

For row 2, number 6 is only possible in cell (7,2)

Single Position

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

Single Position

Either candidate for cell (2,5) forces 7 into cell (2,9).

Forcing Chains

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

Single Candidate

For column 1, Number 7 is only possible in cell (1,2)

Single Position

For row 3, number 2 is only possible in cell (8,3)

Single Position

Either candidate for cell (6,7) forces 4 into cell (7,7).

Forcing Chains

For row 8, number 4 is only possible in cell (1,8)

Single Position

Either candidate for cell (1,6) forces 1 into cell (8,6).

Forcing Chains

Either candidate for cell (9,8) forces 3 into cell (7,8).

Forcing Chains

Number 6 is the only value possible in cell (8,9).

Single Candidate

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

Single Candidate

Number 5 is the only value possible in cell (1,7).

Single Candidate

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

Single Candidate

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

Single Candidate

Number 1 is the only value possible in cell (6,5).

Single Candidate

Number 8 is the only value possible in cell (4,6).

Single Candidate

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

Single Candidate

Number 1 is the only value possible in cell (2,7).

Single Candidate

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

Single Candidate

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

Single Candidate

Number 3 is the only value possible in cell (6,7).

Single Candidate

Number 6 is the only value possible in cell (3,8).

Single Candidate

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

Single Candidate

Number 1 is the only value possible in cell (5,8).

Single Candidate

Number 8 is the only value possible in cell (5,1).

Single Candidate

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

Single Candidate

Number 5 is the only value possible in cell (8,1).

Single Candidate

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

Single Candidate

Number 5 is the only value possible in cell (4,2).

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

Number 9 is the only value possible in cell (8,4).

Single Candidate

Number 8 is the only value possible in cell (3,4).

Single Candidate

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

Single Candidate

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

Single Candidate

Number 8 is the only value possible in cell (7,5).

Single Candidate

Number 3 is the only value possible in cell (8,5).

Single Candidate

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

Single Candidate

Number 5 is the only value possible in cell (9,8).

Single Candidate