Variations on Advanced Sudoku Logic Puzzles (Vol 1) Step-by-Step Instructions for Puzzle 124   (126/225) Diff: 29/9.6312.3243.11D1.1114.9976.4446.8465 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 4 in the 8th row is at (7, 8).
• The only spot left for 7 in the 12th row is at (11, 12).
• The only spot left for E in the 5th column is at (5, 13).
• The only spot left for 2 in the 13th column is at (13, 1).
• The only spot left for A in the 2nd 3x5 rectangle is at (4, 1).
• The only spot left for B in the 5th 3x5 rectangle is at (14, 3).
• The only spot left for D in the 8th 3x5 rectangle is at (8, 10).
• The only spot left for B in the 9th 3x5 rectangle is at (12, 7).
• The only spot left for 8 in the 10th 3x5 rectangle is at (15, 6).
• The only spot left for 4 in the 11th 3x5 rectangle is at (2, 15).
• The only spot left for B in the 13th 3x5 rectangle is at (7, 14).
• The only spot left for A in the 13th 3x5 rectangle is at (9, 12).
• The only spot left for 7 in the 15th 3x5 rectangle is at (14, 15).

Step 2. There are 6 independent moves.

• The only spot left for 4 in the 13th row is at (15, 13).
• The only spot left for D in the 13th row is at (12, 13).
• The only spot left for 8 in the 2nd column is at (2, 1).
• The only spot left for D in the 3rd column is at (3, 6).
• The only spot left for 7 in the 9th 3x5 rectangle is at (12, 8).
• The only spot left for 3 in the 10th 3x5 rectangle is at (15, 7).

Step 3. There are 3 independent moves.

• The only spot left for 3 in the 8th column is at (8, 5).
• The only spot left for 8 in the 3rd 3x5 rectangle is at (9, 3).
• The only spot left for 3 in the 9th 3x5 rectangle is at (12, 6).

Step 4. There is 1 independent move.

• The only spot left for 3 in the 4th 3x5 rectangle is at (10, 3).

Step 5. There are 2 independent moves.

• The only spot left for 6 in the 3rd row is at (7, 3).
• The only spot left for 2 in the 4th 3x5 rectangle is at (12, 3).

Step 6. There are 3 independent moves.

• The only spot left for 1 in the 3rd row is at (4, 3).
• The only spot left for 1 in the 12th column is at (12, 5).
• The only spot left for 9 in the 3rd 3x5 rectangle is at (7, 4).

Step 7. There are 2 independent moves.

• The only spot left for 5 in the 3rd row is at (3, 3).
• The only spot left for E in the 7th column is at (7, 6).

Step 8. There are 4 independent moves.

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

Step 9. There are 3 independent moves.

• The only spot left for 2 in the 9th row is at (14, 9).
• The only spot left for E in the 11th row is at (14, 11).
• The only spot left for A in the 10th 3x5 rectangle is at (13, 10).

Step 10. There is 1 independent move.

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

Step 11. There is 1 independent move.

• The only spot left for A in the 9th 3x5 rectangle is at (11, 6).

Step 12. There are 6 independent moves.

• 8 must be placed at (14, 14) because it is the only value left that is not already in the 14th row, the 14th column or the 15th 3x5 rectangle.
• 1 must be placed at (6, 6) because it is the only value left that is not already in the 6th row, the 6th column or the 7th 3x5 rectangle.
• 8 must be placed at (13, 4) because it is the only value left that is not already in the 4th row, the 13th column or the 5th 3x5 rectangle.
• 0 must be placed at (5, 2) because it is the only value left that is not already in the 2nd row, the 5th column or the 2nd 3x5 rectangle.
• 6 must be placed at (11, 1) because it is the only value left that is not already in the 1st row, the 11th column or the 4th 3x5 rectangle.
• 1 must be placed at (8, 1) because it is the only value left that is not already in the 1st row, the 8th column or the 3rd 3x5 rectangle.

Step 13. There is 1 independent move.

• The only spot left for 1 in the 1st column is at (1, 8).

Step 14. There is 1 independent move.

• The only spot left for 1 in the 11th column is at (11, 9).

Step 15. There is 1 independent move.

• The only spot left for 1 in the 8th 3x5 rectangle is at (9, 7).

Step 16. There is 1 independent move.

• The only spot left for C in the 7th row is at (8, 7).

Step 17. There are 4 independent moves.

• The only spot left for C in the 2nd row is at (15, 2).
• The only spot left for C in the 7th column is at (7, 13).
• The only spot left for C in the 3rd 3x5 rectangle is at (9, 5).
• The only spot left for 0 in the 8th 3x5 rectangle is at (8, 9).

Step 18. There are 10 independent moves.

• The only spot left for 7 in the 5th row is at (5, 5).
• The only spot left for C in the 9th row is at (3, 9).
• The only spot left for C in the 15th row is at (1, 15).
• The only spot left for 3 in the 7th column is at (7, 10).
• The only spot left for E in the 9th column is at (9, 14).
• The only spot left for 7 in the 3rd 3x5 rectangle is at (9, 1).
• The only spot left for 5 in the 8th 3x5 rectangle is at (9, 9).
• The only spot left for C in the 10th 3x5 rectangle is at (14, 8).
• The only spot left for 3 in the 13th 3x5 rectangle is at (9, 13).
• The only spot left for C in the 15th 3x5 rectangle is at (13, 11).

Step 19. There are 9 independent moves.

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

Step 20. There are 7 independent moves.

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

Step 21. There are 6 independent moves.

• The only spot left for 9 in the 5th row is at (2, 5).
• The only spot left for 2 in the 11th row is at (10, 11).
• The only spot left for 6 in the 6th 3x5 rectangle is at (1, 6).
• The only spot left for 0 in the 7th 3x5 rectangle is at (6, 7).
• The only spot left for 0 in the 9th 3x5 rectangle is at (11, 8).
• The only spot left for B in the 15th 3x5 rectangle is at (15, 15).

Step 22. There are 4 independent moves.

• The only spot left for 6 in the 5th row is at (14, 5).
• The only spot left for 0 in the 11th row is at (4, 11).
• The only spot left for B in the 4th column is at (4, 12).
• The only spot left for 6 in the 1st 3x5 rectangle is at (2, 2).

Step 23. There are 4 independent moves.

• The only spot left for D in the 5th row is at (1, 5).
• The only spot left for 6 in the 2nd 3x5 rectangle is at (6, 4).
• The only spot left for D in the 5th 3x5 rectangle is at (14, 4).
• The only spot left for 9 in the 12th 3x5 rectangle is at (4, 15).

Step 24. There are 4 independent moves.

• The only spot left for 5 in the 4th row is at (11, 4).
• The only spot left for E in the 5th row is at (15, 5).
• The only spot left for 5 in the 4th column is at (4, 14).
• The only spot left for 5 in the 2nd 3x5 rectangle is at (6, 2).

Step 25. There are 6 independent moves.

• The only spot left for 4 in the 4th row is at (8, 4).
• The only spot left for A in the 5th row is at (10, 5).
• The only spot left for 5 in the 11th row is at (12, 11).
• The only spot left for 4 in the 4th 3x5 rectangle is at (11, 2).
• The only spot left for A in the 5th 3x5 rectangle is at (15, 4).
• The only spot left for 5 in the 13th 3x5 rectangle is at (8, 15).

Step 26. There are 8 independent moves.

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

Step 27. There are 4 independent moves.

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

Step 28. There are 6 independent moves.

• The only spot left for 1 in the 12th row is at (3, 12).
• The only spot left for 8 in the 15th row is at (10, 15).
• The only spot left for B in the 5th column is at (5, 10).
• The only spot left for B in the 2nd 3x5 rectangle is at (6, 1).
• The only spot left for 8 in the 12th 3x5 rectangle is at (6, 12).
• The only spot left for 1 in the 14th 3x5 rectangle is at (10, 14).

Step 29. There are 5 independent moves.

• The only spot left for 0 in the 14th row is at (3, 14).
• The only spot left for 4 in the 7th 3x5 rectangle is at (6, 10).
• The only spot left for 8 in the 11th 3x5 rectangle is at (3, 13).
• The only spot left for 4 in the 12th 3x5 rectangle is at (5, 12).
• The only spot left for 0 in the 14th 3x5 rectangle is at (10, 13).