Variations on Intermediate Sudoku Logic Puzzles (Vol 1) Step-by-Step Instructions for Puzzle 181   (17/49) Diff: 2/91 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-7D' puzzles.

Step 1. There are 16 independent moves.

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

Step 2. There is 1 independent move.

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