Number 7 is the only value possible in cell (8,1).

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

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

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

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

For column 8, Number 1 is only possible in cell (8,5)

For row 6, number 1 is only possible in cell (4,6)

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

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

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

For column 2, Number 8 is only possible in cell (2,9)

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

For column 5, Number 4 is only possible in cell (5,9)

For column 5, Number 6 is only possible in cell (5,3)

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

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

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

Number 8 is the only value possible in cell (3,1).

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

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

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

Number 1 is the only value possible in cell (9,2).

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

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

For row 5, number 8 is only possible in cell (4,5)

For row 8, number 8 is only possible in cell (7,8)

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

For column 7, Number 9 is only possible in cell (7,3)

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

For row 7, number 5 is only possible in cell (1,7)

Number 9 is the only value possible in cell (1,8).

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

For box 8, candidates for 7 are all in column 4, so you can remove candidates from other blocks.

For row 4, number 7 is only possible in cell (6,4)

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

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

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

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

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

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

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

Number 9 is the only value possible in cell (6,5).

Number 7 is the only value possible in cell (2,6).

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

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

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

Number 6 is the only value possible in cell (9,5).

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

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

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

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

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

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