How to Solve LinkedIn Mini Sudoku #178: Half Rings

Game: LinkedIn Mini Sudoku | Puzzle #178: Half Rings | Published: February 5, 2026

The Half Rings puzzle presents a 6x6 Sudoku with nine clue cells strategically placed across the grid. This intermediate-level puzzle requires systematic elimination and logical deduction to reveal all 36 numbers. Let's work through the solving process step by step.

Understanding the Starting Position

The puzzle begins with nine prefilled cells:

• Row 1: 1 in column 2, 4 in column 5
• Row 2: 2 in column 3, 3 in column 4
• Row 3: 6 in column 1, 4 in column 6
• Row 4: 5 in column 2, 3 in column 5
• Row 5: 4 in column 2, 2 in column 5
• Row 6: 3 in column 1, 1 in column 6

These clues anchor our solving strategy by limiting candidate possibilities in rows, columns, and 2x3 boxes.

Phase 1: Identifying Naked Singles

Begin by scanning for cells with only one possible candidate—a technique called elimination scanning. Look at each empty cell and determine which numbers are already used in its row, column, and 2x3 box.

Row 1 Analysis

Row 1 contains 1 and 4, missing: 2, 3, 5, 6

• Column 1 already has 6 in row 3 and 3 in row 6, so row 1, column 1 cannot be 3 or 6
• The top-left 2x3 box contains 1 and 2, ruling those out
• Column 1, row 1 must be 5 (the only remaining candidate)

Continuing this elimination process across row 1's remaining empty cells reveals where each number must logically fit based on row, column, and box constraints.

Row 3 Analysis

Row 3 starts with 6 and 4. The middle-left box already contains the 6, which helps eliminate candidates from neighboring cells.

• Row 3, column 2 cannot contain numbers already in column 2 (1, 5, 4)
• Row 3, column 3 requires checking both row constraints and box constraints simultaneously

Phase 2: Cross-Hatching for Multiple Occurrences

When naked singles aren't immediately obvious, use cross-hatching—a scanning method where you focus on individual numbers and find where they must appear in boxes missing them.

Finding All 5s

With 5 appearing in row 4, column 2:

• Eliminate column 2 from candidate positions for 5
• Scan the three 2x3 boxes in column 1-2 to see where 5 must fit
• For boxes that lack a 5, narrow candidates using row and column intersections

Finding All 2s

With 2 appearing in row 2, column 3:

• Eliminate row 2 and column 3 from other 2 positions
• Focus on the top-middle and bottom-middle 2x3 boxes to locate remaining 2s

Phase 3: Box-Line Reduction

When a digit's candidates in a box are restricted to a single row or column, you can eliminate that digit from the same row or column outside the box.

For example, if only one cell in the top-right box can contain a 5, and it's in row 1, then no other cell in row 1 can contain 5—even outside this box.

Phase 4: Constraint Propagation

As you fill cells, watch for cascading eliminations. Completing one cell often forces the placement of several others:

• Filling row 2, column 6 eliminates that candidate from other cells in row 2, column 6, and the middle-right box
• A newly determined cell immediately constrains the box, row, and column it occupies

Strategy Tip: Work the Most Constrained Regions First

Boxes and rows/columns with more filled cells are easier to complete. After placing your initial naked singles, prioritize regions that are already 4 or 5 cells filled—these offer the fewest remaining possibilities and solve quickly.

Solving Pattern Recognition

The Half Rings puzzle's clue arrangement creates a symmetric pattern. Notice how clues in opposite positions (top-left/bottom-right) create balanced constraints. This symmetry often means solving one section suggests candidates for its opposite.

Final Verification

Once all 36 cells are filled, verify the solution by confirming:

• Each row contains 1-6 exactly once
• Each column contains 1-6 exactly once
• Each 2x3 box contains 1-6 exactly once

By combining systematic elimination, cross-hatching, and logical deduction, the Half Rings puzzle reveals itself completely. The key is persistence and remembering that every clue constrains dozens of cell possibilities—leverage those constraints methodically and the solution emerges naturally.