Puzzle   ·   3-steps   ·	Printable Puzzle or with all steps listed.
Difficult Sudoku-8-X Group Puzzle
Share Tweet

The small superscript in each undetermined location is the step number at which the location must be fill before all of the locations with subsequent step numbers can be determined. A detailed description of the moves in each step is given below.

Display the puzzle with superscripts showing just the step number for the first few steps in their empty grid locations.

See the puzzle answer grid.

Deductive steps to solve the puzzle

The moves within each step may be done in any order.

All of the moves within a particular step must be done before all of the moves in the subsequent step can be guaranteed to be completed.

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 .

Step 1. There are 10 independent moves.

• The only spot left for 7 in the 1st column is at (1, 5).
• The only spot left for 2 in the 2nd column is at (2, 3).
• The only spot left for 8 in the 6th column is at (6, 5).
• The only spot left for 8 in the 2nd 4x2 rectangle is at (7, 1).
• The only spot left for 8 in the 4th 4x2 rectangle is at (8, 3).
• The only spot left for 8 in the 7th 4x2 rectangle is at (4, 8).
• The only spot left for 7 in the 8th 4x2 rectangle is at (5, 8).
• The only spot left for 6 in the 1st diagonal is at (7, 7).
• The only spot left for 6 in the 2nd diagonal is at (5, 4).
• The only spot left for 2 in the 2nd diagonal is at (7, 2).

Step 2. There are 2 independent moves.

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

Step 3. There are 2 independent moves.

• The only spot left for 1 in the 1st column is at (1, 3).
• The only spot left for 3 in the 3rd 4x2 rectangle is at (3, 4).

Step 4. There are 2 independent moves.

• The only spot left for 4 in the 1st column is at (1, 8).
• The only spot left for 1 in the 1st diagonal is at (8, 8).

Step 5. There are 4 independent moves.

• The only spot left for 4 in the 2nd column is at (2, 5).
• The only spot left for 5 in the 8th column is at (8, 6).
• The only spot left for 5 in the 8th 4x2 rectangle is at (7, 8).
• The only spot left for 4 in the 8th 4x2 rectangle is at (6, 7).

Step 6. There are 2 independent moves.

• The only spot left for 3 in the 2nd column is at (2, 8).
• The only spot left for 3 in the 8th 4x2 rectangle is at (8, 7).

Step 7. There is 1 independent move.

• 1 must be placed at (5, 1) because it is the only value left that is not already in the 1st row, the 5th column or the 2nd 4x2 rectangle.

Step 8. There is 1 independent move.

• The only spot left for 1 in the 6th column is at (6, 4).

Step 9. There is 1 independent move.

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

Step 10. There are 5 independent moves.

• The only spot left for 4 in the 4th row is at (7, 4).
• The only spot left for 4 in the 4th column is at (4, 1).
• The only spot left for 5 in the 5th 4x2 rectangle is at (3, 5).
• The only spot left for 4 in the 1st diagonal is at (3, 3).
• The only spot left for 5 in the 2nd diagonal is at (6, 3).

Step 11. There are 10 independent moves.

• The only spot left for 1 in the 5th row is at (7, 5).
• The only spot left for 1 in the 3rd column is at (3, 2).
• The only spot left for 2 in the 4th column is at (4, 7).
• The only spot left for 3 in the 6th column is at (6, 2).
• The only spot left for 2 in the 1st 4x2 rectangle is at (3, 1).
• The only spot left for 5 in the 2nd 4x2 rectangle is at (5, 2).
• The only spot left for 3 in the 4th 4x2 rectangle is at (5, 3).
• The only spot left for 1 in the 5th 4x2 rectangle is at (4, 6).
• The only spot left for 4 in the 6th 4x2 rectangle is at (5, 6).
• The only spot left for 3 in the 2nd diagonal is at (4, 5).

Step 12. There are 3 independent moves.

• The only spot left for 7 in the 1st 4x2 rectangle is at (4, 2).
• The only spot left for 3 in the 6th 4x2 rectangle is at (7, 6).
• The only spot left for 7 in the 7th 4x2 rectangle is at (3, 7).

Wednesday October 2, 2024   https://www.grouppuzzles.com