Difficult Sudoku Seven Logic Puzzles (Vol 1) Step-by-Step Instructions for Puzzle 106   (40/49) Diff: 12/232A.2113.2498 Printable puzzle or puzzle with instructions The numbers in the puzzle below refer to the step number at which the value of the location can be deduced. Locations without step numbers contain the initial values found in corresponding puzzle in your edition of the book.

Rows are numbered top to bottom, columns from left to right, and rectangles from left to right and then top to bottom. Coordinates are (col, row). Precise details on numbering within each group are specified in the on-line instructions for 'Sudoku-7B-X' puzzles.

Step 1. There are 2 independent moves.

• The only spot left for 7 in the 5th septomino is at (3, 4).
• The only spot left for 7 in the 2nd diagonal is at (5, 3).

Step 2. There are 3 independent moves.

• The only spot left for 7 in the 1st septomino is at (2, 2).
• The only spot left for 4 in the 3rd septomino is at (6, 3).
• The only spot left for 7 in the 7th septomino is at (6, 7).

Step 3. There are 2 independent moves.

• The only spot left for 4 in the 5th septomino is at (4, 4).
• The only spot left for 7 in the 6th septomino is at (7, 6).

Step 4. There is 1 independent move.

• 2 must be placed at (5, 5) because it is the only value left that is not already in the 5th row, the 5th column, the 5th septomino or the 1st diagonal.

Step 5. There are 2 independent moves.

• The only spot left for 2 in the 2nd septomino is at (3, 1).
• The only spot left for 2 in the 6th septomino is at (7, 4).

Step 6. There is 1 independent move.

• The only spot left for 1 in the 6th septomino is at (7, 7).

Step 7. There is 1 independent move.

• The only spot left for 1 in the 2nd diagonal is at (3, 5).

Step 8. There are 3 independent moves.

• The only spot left for 1 in the 2nd septomino is at (4, 2).
• The only spot left for 1 in the 4th septomino is at (2, 4).
• The only spot left for 3 in the 5th septomino is at (4, 3).

Step 9. There are 2 independent moves.

• The only spot left for 1 in the 1st septomino is at (1, 3).
• The only spot left for 3 in the 2nd septomino is at (3, 2).

Step 10. There are 4 independent moves.

• The only spot left for 2 in the 1st column is at (1, 6).
• The only spot left for 2 in the 1st septomino is at (2, 3).
• The only spot left for 5 in the 2nd septomino is at (3, 3).
• The only spot left for 3 in the 3rd septomino is at (7, 1).

Step 11. There are 11 independent moves.

• The only spot left for 5 in the 1st row is at (2, 1).
• The only spot left for 6 in the 3rd row is at (7, 3).
• The only spot left for 4 in the 6th row is at (3, 6).
• The only spot left for 4 in the 1st column is at (1, 2).
• The only spot left for 3 in the 1st septomino is at (1, 4).
• The only spot left for 5 in the 3rd septomino is at (7, 2).
• The only spot left for 4 in the 4th septomino is at (2, 7).
• The only spot left for 3 in the 4th septomino is at (2, 5).
• The only spot left for 5 in the 6th septomino is at (6, 5).
• The only spot left for 2 in the 7th septomino is at (4, 7).
• The only spot left for 3 in the 1st diagonal is at (6, 6).

Step 12. There are 8 independent moves.

• The only spot left for 6 in the 2nd row is at (5, 2).
• The only spot left for 6 in the 2nd column is at (2, 6).
• The only spot left for 4 in the 2nd septomino is at (5, 1).
• The only spot left for 6 in the 6th septomino is at (6, 4).
• The only spot left for 6 in the 7th septomino is at (3, 7).
• The only spot left for 5 in the 7th septomino is at (4, 6).
• The only spot left for 6 in the 1st diagonal is at (1, 1).
• The only spot left for 5 in the 2nd diagonal is at (1, 7).