Variations on Advanced Sudoku Logic Puzzles (Vol 1) Step-by-Step Instructions for Puzzle 123   (129/225) Diff: 28/9884.2111.C426.4496.5331.1243.6993 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-15up' puzzles.

Step 1. There are 13 independent moves.

• The only spot left for B in the 12th row is at (3, 12).
• The only spot left for 5 in the 1st 3x5 rectangle is at (2, 5).
• The only spot left for C in the 3rd 3x5 rectangle is at (8, 4).
• The only spot left for B in the 3rd 3x5 rectangle is at (9, 1).
• The only spot left for 0 in the 7th 3x5 rectangle is at (6, 9).
• The only spot left for A in the 9th 3x5 rectangle is at (12, 8).
• The only spot left for 2 in the 9th 3x5 rectangle is at (12, 7).
• The only spot left for 8 in the 10th 3x5 rectangle is at (14, 10).
• The only spot left for 9 in the 12th 3x5 rectangle is at (4, 12).
• The only spot left for 2 in the 13th 3x5 rectangle is at (8, 14).
• The only spot left for 5 in the 13th 3x5 rectangle is at (7, 12).
• The only spot left for B in the 14th 3x5 rectangle is at (11, 15).
• The only spot left for 0 in the 15th 3x5 rectangle is at (15, 11).

Step 2. There are 8 independent moves.

• The only spot left for 2 in the 3rd row is at (5, 3).
• The only spot left for 0 in the 5th row is at (10, 5).
• The only spot left for B in the 8th row is at (1, 8).
• The only spot left for D in the 8th column is at (8, 12).
• The only spot left for 1 in the 9th column is at (9, 15).
• The only spot left for 5 in the 12th column is at (12, 14).
• The only spot left for 0 in the 1st 3x5 rectangle is at (2, 3).
• The only spot left for 5 in the 4th 3x5 rectangle is at (10, 2).

Step 3. There are 8 independent moves.

• The only spot left for 0 in the 4th row is at (13, 4).
• The only spot left for 8 in the 12th row is at (9, 12).
• The only spot left for D in the 13th row is at (11, 13).
• The only spot left for 8 in the 8th column is at (8, 6).
• The only spot left for B in the 2nd 3x5 rectangle is at (4, 3).
• The only spot left for 0 in the 2nd 3x5 rectangle is at (4, 1).
• The only spot left for A in the 13th 3x5 rectangle is at (8, 15).
• The only spot left for D in the 15th 3x5 rectangle is at (13, 14).

Step 4. There are 4 independent moves.

• The only spot left for 7 in the 3rd row is at (12, 3).
• The only spot left for E in the 12th row is at (12, 12).
• The only spot left for 7 in the 2nd 3x5 rectangle is at (5, 1).
• The only spot left for 8 in the 6th 3x5 rectangle is at (2, 9).

Step 5. There are 2 independent moves.

• The only spot left for 6 in the 12th column is at (12, 10).
• The only spot left for 7 in the 5th 3x5 rectangle is at (14, 4).

Step 6. There is 1 independent move.

• The only spot left for D in the 9th 3x5 rectangle is at (12, 9).

Step 7. There is 1 independent move.

• The only spot left for 3 in the 12th column is at (12, 4).

Step 8. There is 1 independent move.

• The only spot left for 3 in the 3rd row is at (7, 3).

Step 9. There are 3 independent moves.

• 4 must be placed at (2, 15) because it is the only value left that is not already in the 15th row, the 2nd column or the 11th 3x5 rectangle.
• 4 must be placed at (14, 12) because it is the only value left that is not already in the 12th row, the 14th column or the 15th 3x5 rectangle.
• C must be placed at (15, 8) because it is the only value left that is not already in the 8th row, the 15th column or the 10th 3x5 rectangle.

Step 10. There are 4 independent moves.

• The only spot left for 4 in the 1st column is at (1, 1).
• The only spot left for C in the 13th column is at (13, 15).
• The only spot left for C in the 5th 3x5 rectangle is at (14, 5).
• The only spot left for 4 in the 12th 3x5 rectangle is at (6, 11).

Step 11. There are 2 independent moves.

• The only spot left for 4 in the 13th column is at (13, 7).
• The only spot left for 9 in the 15th 3x5 rectangle is at (14, 15).

Step 12. There are 6 independent moves.

• The only spot left for 4 in the 10th row is at (7, 10).
• The only spot left for 5 in the 15th row is at (5, 15).
• The only spot left for 5 in the 14th column is at (14, 1).
• The only spot left for 4 in the 6th 3x5 rectangle is at (3, 9).
• The only spot left for 9 in the 10th 3x5 rectangle is at (13, 8).
• The only spot left for 5 in the 15th 3x5 rectangle is at (15, 13).

Step 13. There are 4 independent moves.

• The only spot left for 1 in the 9th row is at (10, 9).
• The only spot left for 9 in the 9th column is at (9, 7).
• The only spot left for 5 in the 7th 3x5 rectangle is at (4, 10).
• The only spot left for 5 in the 10th 3x5 rectangle is at (13, 6).

Step 14. There are 4 independent moves.

• The only spot left for 3 in the 9th row is at (15, 9).
• The only spot left for C in the 9th row is at (9, 9).
• The only spot left for 7 in the 13th column is at (13, 12).
• The only spot left for D in the 8th 3x5 rectangle is at (9, 8).

Step 15. There are 9 independent moves.

• The only spot left for 3 in the 5th row is at (6, 5).
• The only spot left for E in the 8th row is at (14, 8).
• The only spot left for 7 in the 9th row is at (7, 9).
• The only spot left for A in the 13th column is at (13, 1).
• The only spot left for 3 in the 5th 3x5 rectangle is at (14, 2).
• The only spot left for D in the 6th 3x5 rectangle is at (2, 10).
• The only spot left for 6 in the 8th 3x5 rectangle is at (9, 6).
• The only spot left for 7 in the 10th 3x5 rectangle is at (15, 10).
• The only spot left for A in the 15th 3x5 rectangle is at (15, 12).

Step 16. There are 6 independent moves.

• The only spot left for 1 in the 10th row is at (6, 10).
• The only spot left for 3 in the 15th row is at (3, 15).
• The only spot left for 6 in the 7th 3x5 rectangle is at (5, 7).
• The only spot left for E in the 8th 3x5 rectangle is at (7, 7).
• The only spot left for 1 in the 10th 3x5 rectangle is at (14, 7).
• The only spot left for 3 in the 12th 3x5 rectangle is at (4, 13).

Step 17. There are 5 independent moves.

• The only spot left for 3 in the 7th row is at (10, 7).
• The only spot left for 8 in the 13th row is at (1, 13).
• The only spot left for 7 in the 15th row is at (6, 15).
• The only spot left for 3 in the 6th 3x5 rectangle is at (1, 6).
• The only spot left for 8 in the 12th 3x5 rectangle is at (4, 11).

Step 18. There are 3 independent moves.

• The only spot left for 7 in the 6th row is at (3, 6).
• The only spot left for C in the 7th row is at (3, 7).
• The only spot left for 7 in the 7th 3x5 rectangle is at (4, 7).

Step 19. There are 3 independent moves.

• The only spot left for 7 in the 13th row is at (9, 13).
• The only spot left for D in the 4th column is at (4, 2).
• The only spot left for D in the 7th 3x5 rectangle is at (6, 7).

Step 20. There is 1 independent move.

• The only spot left for E in the 13th 3x5 rectangle is at (9, 11).

Step 21. There is 1 independent move.

• The only spot left for E in the 2nd column is at (2, 14).

Step 22. There are 2 independent moves.

• The only spot left for 1 in the 2nd column is at (2, 8).
• The only spot left for E in the 12th 3x5 rectangle is at (6, 13).

Step 23. There are 4 independent moves.

• The only spot left for 6 in the 2nd column is at (2, 11).
• The only spot left for A in the 6th column is at (6, 2).
• The only spot left for 6 in the 6th 3x5 rectangle is at (3, 8).
• The only spot left for A in the 12th 3x5 rectangle is at (5, 14).

Step 24. There are 3 independent moves.

• The only spot left for 6 in the 11th column is at (11, 1).
• The only spot left for A in the 3rd 3x5 rectangle is at (7, 5).
• The only spot left for 6 in the 14th 3x5 rectangle is at (10, 13).

Step 25. There are 6 independent moves.

• The only spot left for 6 in the 3rd row is at (8, 3).
• The only spot left for 9 in the 5th row is at (11, 5).
• The only spot left for A in the 13th row is at (3, 13).
• The only spot left for 9 in the 3rd 3x5 rectangle is at (7, 2).
• The only spot left for 2 in the 4th 3x5 rectangle is at (11, 4).
• The only spot left for 6 in the 5th 3x5 rectangle is at (15, 2).

Step 26. There are 11 independent moves.

• The only spot left for 4 in the 2nd row is at (5, 2).
• The only spot left for 2 in the 2nd row is at (3, 2).
• The only spot left for 1 in the 3rd row is at (1, 3).
• The only spot left for E in the 5th row is at (5, 5).
• The only spot left for A in the 11th column is at (11, 11).
• The only spot left for E in the 11th column is at (11, 6).
• The only spot left for 1 in the 3rd 3x5 rectangle is at (8, 1).
• The only spot left for E in the 4th 3x5 rectangle is at (10, 4).
• The only spot left for 4 in the 5th 3x5 rectangle is at (15, 5).
• The only spot left for 2 in the 5th 3x5 rectangle is at (15, 1).
• The only spot left for 9 in the 9th 3x5 rectangle is at (10, 10).

Step 27. There are 11 independent moves.

• The only spot left for B in the 10th row is at (5, 10).
• The only spot left for 7 in the 11th row is at (1, 11).
• The only spot left for C in the 11th column is at (11, 10).
• The only spot left for A in the 1st 3x5 rectangle is at (1, 4).
• The only spot left for E in the 1st 3x5 rectangle is at (3, 1).
• The only spot left for E in the 3rd 3x5 rectangle is at (8, 2).
• The only spot left for A in the 4th 3x5 rectangle is at (10, 3).
• The only spot left for B in the 9th 3x5 rectangle is at (10, 6).
• The only spot left for 1 in the 11th 3x5 rectangle is at (3, 14).
• The only spot left for 7 in the 14th 3x5 rectangle is at (11, 14).
• The only spot left for C in the 14th 3x5 rectangle is at (10, 11).

Step 28. There are 3 independent moves.

• The only spot left for 9 in the 1st 3x5 rectangle is at (3, 4).
• The only spot left for C in the 7th 3x5 rectangle is at (5, 6).
• The only spot left for 9 in the 11th 3x5 rectangle is at (1, 14).