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

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

For row 3, number 1 is only possible in cell (5,3)

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

For row 1, number 8 is only possible in cell (7,1)

For row 6, number 8 is only possible in cell (3,6)

For row 7, number 8 is only possible in cell (2,7)

For row 9, number 8 is only possible in cell (6,9)

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

For row 7, number 4 is only possible in cell (1,7)

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

For row 5, number 4 is only possible in cell (2,5)

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

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

For row 1, number 2 is only possible in cell (4,1)

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

For row 6, number 2 is only possible in cell (8,6)

For row 5, number 2 is only possible in cell (3,5)

For box 4, candidates for 3 are all in row 4, so you can remove candidates from other blocks.

For box 4, candidates for 6 are all in column 1, so you can remove candidates from other blocks.

For box 7, candidates for 6 are all in row 9, so you can remove candidates from other blocks.

Number 5 is the only value possible in cell (7,9).

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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