Step-by-Step Solution

for Thursday 19th December Fiendish

Number 5 is the only value possible in cell (6,8).

Single Candidate

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

Single Position

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

Single Position

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

Single Position

For row 6, number 5 is only possible in cell (8,6)

Single Position

For row 9, number 5 is only possible in cell (1,9)

Single Position

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

Single Position

For column 1, Number 4 is only possible in cell (1,6)

Single Position

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

Single Position

For row 5, number 2 is only possible in cell (1,5)

Single Position

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

Single Position

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

Single Candidate

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

Single Position

For column 9, Number 6 is only possible in cell (9,7)

Single Position

For box 7, candidates for 1 are all in column 3, so you can remove candidates from other blocks.

Candidate Lines

Naked Pair for 7 and 9, can remove these as candidates from other cells.

Naked Pairs

For box 4, Number 7 is only possible in cell (3,5)

Single Position

For blocks 1 and 4, candidates for 9 are all in the same two columns (3 and 1)

Double Pairs

Candidates for 9 in boxes 4 and 5 force the candidates in box 6 to be in the remaining line.

Multiple Lines

Naked Pair for 1 and 4, can remove these as candidates from other cells.

Naked Pairs

Naked Pair for 1 and 7, can remove these as candidates from other cells.

Naked Pairs

Candidates for 1 in boxes 5 and 8 force the candidates in box 2 to be in the remaining line.

Multiple Lines

Naked Pair for 7 and 9, can remove these as candidates from other cells.

Naked Pairs

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

Single Candidate

For row 4, number 9 is only possible in cell (1,4)

Single Position

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

Single Candidate

Number 7 is the only value possible in cell (4,2).

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

Number 6 is the only value possible in cell (2,1).

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

Number 1 is the only value possible in cell (4,3).

Single Candidate

Number 2 is the only value possible in cell (5,3).

Single Candidate

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

Single Candidate

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

Single Candidate

Number 8 is the only value possible in cell (6,5).

Single Candidate

Number 1 is the only value possible in cell (6,4).

Single Candidate

Number 3 is the only value possible in cell (7,5).

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

Number 6 is the only value possible in cell (5,4).

Single Candidate

Number 8 is the only value possible in cell (2,6).

Single Candidate

Number 3 is the only value possible in cell (2,4).

Single Candidate

Number 4 is the only value possible in cell (6,7).

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate

Number 1 is the only value possible in cell (5,9).

Single Candidate

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

Single Candidate

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

Single Candidate

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

Single Candidate