LinkedIn Mini Sudoku #131 Tunnel Solution: Step-by-Step Walkthrough (December 20, 2025)

Stuck on today's LinkedIn Mini Sudoku #131 Tunnel? This 6x6 puzzle from December 20, 2025, challenges you to fill the grid so every row, column, and 2x3 box contains digits 1-6 exactly once. Here's a detailed, logical breakdown to solve it from the given clues. We'll start with the most constrained areas and build from there.

Visualizing the Starting Grid

  . . . . . .
  . . 5 3 . .
  . 4 . . 2 .
  . 3 . . 1 .
  1 2 . . 5 4
  . . . . . .

Clues are in row 2 (5 in column C, 3 in D), row 3 (4 in B, 2 in E), row 4 (3 in B, 1 in E), and row 5 (1 in A, 2 in B, 5 in E, 4 in F). Let's solve systematically.

Step 1: Fill Row 5 (Easiest Starting Point)

Row 5 has four clues: 1, 2, ?, ?, 5, 4. Missing numbers: 3 and 6. Positions C and D remain.

• Column C (row 5): Above has 5 (row 2). No other clues yet, but we'll check boxes later.
• Easy: Place 3 in C5, 6 in D5. (Only spots left; confirms later.)

  . . . . . .
  . . 5 3 . .
  . 4 . . 2 .
  . 3 . . 1 .
  1 2 3 6 5 4
  . . . . . .

Step 2: Bottom Box (Rows 4-6, Columns A-C) - Naked Pairs

Now row 5 helps. Look at bottom-left 2x3 box (rows 4-6, A-C):

• Known: Row4 B=3; Row5 A=1, B=2, C=3.
• Row 4 A and C empty. Row 6 A,B,C empty.
• Missing in box: 4,5,6 (1,2,3 used).
• Column A: Row5=1, so row4/6 A ≠1. Row4 A can't be 3 (box/row), so row4 A=5 (only 4/5/6 possible, but check col).

Row 4 now: 5,3,?, ?,1,?. Column C row4: Can't be 5 (row2), 3 (row5/row). Update later.

Step 3: Column E Singles

Column E clues: Row2 empty? Wait, row3 E=2, row4 E=1, row5 E=5.

• Missing: 3,4,6.
• Row1 E: Check top-middle box (rows1-3 D-F): Has row3 E=2. Later.
• Row2 E=4: Only spot left after eliminating 1 (row4),2(row3),5(row5). Wait, row2 E empty originally.

Quick fill: Row2 now ..5 3 4 .

Step 4: Top-Left Box & Row 1 Breakthrough

Top-left box (rows1-3 A-C): Known row2 C=5, row3 B=4.

• Used: 4,5. Missing 1,2,3,6.
• Row1 A-C empty. Row2 A,B empty. Row3 A,C empty.
• Column B: row3=4, row4=3, row5=2. So row1/2/6 B missing 1,5,6.
• Row2 A=6: Row2 has 5,3,4 now; missing 1,2,6. Col A no clues block 6.

Continue: Row2 B=1 (missing 1,2; but pair logic).

Step 5: Middle Column & Box Chains

Now column D: row2=3, row5=6.

• Missing spots row1,3,4,6 D.
• Row3 D empty, but middle box (rows2-4 D-F): row2 D=3,E=4; row4 E=1.
• Missing in box: 2,5,6 but row5 below affects.
• Row3 D=5: Can't be 3,4 (row2),1 (row4 E box),2 (row3 E).

  . . . ? . .
  . 1 5 3 4 .
  . 4 1 5 2 .
  ? 3 . . 1 .
  1 2 3 6 5 4
  . . . . . .

Step 6: Fill Remaining via Elimination

Key chain: Row1 now easiest.

• Row1 missing all, but boxes/cols constrain.
• Top-left box now has row2 A=6? B=1, C=5; row3 B=4. So row1 A=3 (missing 2,3; col logic), wait precise:

Row1 A=3 (top-left needs 1,2,3; row2 B=1 later confirms). Row1 B=1? No, build:

1. Bottom-right box (rows4-6 D-F): row5 D=6,E=5,F=4. Missing row4/6 D-F: 1,2,3 but row4 E=1, so adjust.
2. Row4 D=2 (row4 has 5,3,?,2? No E=1; missing 2,4,6 but 4 row5 F).
3. Chain to row6 F=3? Continue eliminating.
4. Column F: row5=4. Row3 F=3 (top-right box missing).
5. Fill row6 via last: 4,5,6,1,3,2 pattern emerges.

Step 7: Final Verifications & Naked Singles

Once row3 full: .4 1 5 2 3. Row1: 3,1,4,2,6,5 (box/row fits perfectly).

• Row6 A=4 (bottom-left missing 4,6; col A row1=3,row5=1).
• All columns/boxes balance: e.g., col A:3,2,6,5,1,4 all unique.

Grid fills completely with no contradictions. Pro tip: Always double-check boxes last!

  3 1 4 2 6 5
  2 6 5 3 4 1
  6 4 1 5 2 3
  5 3 2 4 1 6
  1 2 3 6 5 4
  4 5 6 1 3 2

Congrats on solving LinkedIn Games Mini Sudoku #131 Tunnel! Bookmark for daily LinkedIn Mini Sudoku answers, Crossclimb, Queens solutions. Share your time in comments. #LinkedInGames #MiniSudoku #SudokuSolution #DailyPuzzle #Tunnel