Number 4 is the only value possible in cell (9,1).

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

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

For column 3, Number 8 is only possible in cell (3,6)

For row 4, number 9 is only possible in cell (2,4)

For row 7, number 9 is only possible in cell (6,7)

For row 2, number 9 is only possible in cell (5,2)

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

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

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

For box 4, candidates for 5 are all in column 1, so you can remove candidates from other blocks.

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

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

For row 2, number 1 is only possible in cell (3,2)

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

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

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

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

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

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

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

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

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

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

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

Number 4 is the only value possible in cell (6,2).

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

Number 7 is the only value possible in cell (8,6).

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

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

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

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

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

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

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

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

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

Number 3 is the only value possible in cell (7,9).

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