## Step-By-Step Solution:

## Initial Grid | |

First step - add in all possible valid pencilmarks. |

For row 4, number 1 is only possible in cell (5,4) | ||

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

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

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

For column 9, Number 6 is only possible in cell (9,4) | ||

For column 1, Number 4 is only possible in cell (1,5) | ||

For column 6, Number 3 is only possible in cell (6,9) | ||

For box 8, candidates for 7 are all in column 5, so you can remove candidates from other blocks. | ||

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

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

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

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

For column 3, Number 2 is only possible in cell (3,8) | ||

For blocks 6 and 9, candidates for 2 are all in the same two columns (8 and 9) | ||

Candidates for 9 in boxes 5 and 8 force the candidates in box 2 to be in the remaining line. | ||

Hidden Pair for 2 and 4, can remove other candidates from these cells. | ||

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

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

Hidden Pair for 6 and 8, can remove other candidates from these cells. | ||

For blocks 4 and 6, candidates for 9 are all in the same two rows (4 and 6) | ||

Naked Pair for 3 and 5, can remove these as candidates from other cells. | ||

For column 1, Number 3 is only possible in cell (1,8) | ||

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

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

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

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

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

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

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

For row 9, number 5 is only possible in cell (8,9) | ||

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

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

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

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

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

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

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

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

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

Number 8 is the only value possible in cell (2,1). | ||

Number 5 is the only value possible in cell (4,1). | ||

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

Number 2 is the only value possible in cell (5,1). | ||

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

Number 7 is the only value possible in cell (6,1). | ||

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

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

Number 5 is the only value possible in cell (1,2). | ||

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

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

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

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

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

Number 4 is the only value possible in cell (5,3). | ||

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

Number 2 is the only value possible in cell (7,3). | ||

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

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

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

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

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

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

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

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

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

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