Difficult Sudoku Five Logic Puzzles (Vol 1) Step-by-Step Instructions for Puzzle 123   (20/25) Diff: 10/23.1121.1351 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-5B' puzzles.

Step 1. There are 2 independent moves.

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

Step 2. There are 3 independent moves.

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

Step 3. There is 1 independent move.

• The only spot left for 4 in the 3rd pentomino is at (4, 3).

Step 4. There is 1 independent move.

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

Step 5. There are 2 independent moves.

• The only spot left for 1 in the 5th column is at (5, 1).
• The only spot left for 1 in the 5th pentomino is at (3, 5).

Step 6. There is 1 independent move.

• The only spot left for 3 in the 5th row is at (4, 5).

Step 7. There is 1 independent move.

• The only spot left for 3 in the 5th column is at (5, 2).

Step 8. There are 3 independent moves.

• The only spot left for 2 in the 2nd row is at (3, 2).
• The only spot left for 3 in the 3rd row is at (2, 3).
• The only spot left for 3 in the 2nd pentomino is at (3, 1).

Step 9. There are 5 independent moves.

• The only spot left for 2 in the 3rd row is at (5, 3).
• The only spot left for 5 in the 3rd column is at (3, 3).
• The only spot left for 2 in the 1st pentomino is at (2, 1).
• The only spot left for 5 in the 2nd pentomino is at (4, 1).
• The only spot left for 2 in the 3rd pentomino is at (4, 4).

Step 10. There is 1 independent move.

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