LinkedIn Mini Sudoku #121 (Ten) - Step-by-Step Solving Guide for December 10, 2025

Welcome to the detailed walkthrough for solving the LinkedIn Mini Sudoku #121 (Ten) published on December 10, 2025, a 6x6 Sudoku puzzle challenge. This guide will focus on the logical reasoning behind filling each empty cell, moving from the initial clues to a fully solved grid.

The puzzle consists of a 6x6 grid divided into six regions of 2 rows by 3 columns, where each row, column, and region must contain the digits 1 to 6 exactly once. Some cells are prefilled as clues:

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

We solve systematically by checking rows, columns, and boxes for missing digits, applying logical elimination and the strategy of single possibility and exclusion.

Step 1: Fill what can’t be anywhere else (Use Given Clues and Boxes)

Begin with rows or boxes with the most clues. For example, in row 2, we already have digits 1, 4, and 6 filled. The missing digits are 2, 3, and 5.

Looking in the 2x3 box containing row 2, columns 1-3, we find digits 1 and 2 present, limiting where 3 and 5 can go. Since the first column in that box contains '1' (row 2) and '2' (row 3), 3 and 5 must fit into the remaining cells of that box by exclusion.

Step 2: Use Column Constraints

Check columns for missing numbers. In the first column, digits 1, 2, 3, and 4 appear in rows 2 to 5, so only 5 and 6 are missing in rows 1 and 6 respectively. The empty cells in row 1 and 6 (columns 1 to 6) can be narrowed based on missing numbers in their respective columns.

Step 3: Incremental Filling Using Region and Row Checks

In the third box (rows 1-2, columns 4-6), numbers 4 and 6 are occupied. The missing digits are 2, 3, and 5. Since columns 4-6 in rows 1 and 2 are incomplete, we use the row and column presence of these digits to logically place the missing ones.

Step 4: Identify Naked Singles

Cells where only one digit can fit are called naked singles, for example, if a cell’s row, column, and box already contain 1, 2, 3, 4, and 6, then by deduction it must be 5. Such spots become obvious as you fill more cells.

Step 5: Consistent Cross Verification

Every time a digit is placed, verify that the same digit does not repeat in its row, column, or box. If a conflict arises, re-examine previous placements, as Sudoku is iterative logic.

Step 6: Example Reasoning on Key Cells

Consider row 3, column 2: The column contains digits 1, 5, and 6; the box includes 2 and 4; and the row has 2, 4, and 5. The only digit missing in all three groups here is 1, so that cell is confidently assigned 1.

Similarly, examine row 6, column 4. The row contains already 3 and 1, and column 4 contains digits 4 and 5 in other positions, leaving 2 as the only candidate here.

Step 7: Closing In on the Solution

By continuously applying these logical steps across all empty cells—checking for uniqueness within rows, columns, and boxes, and narrowing candidates by elimination—the puzzle gradually fills up.

Row 1: 6, 4, 3, 2, 5, 1
Row 2: 1, 2, 5, 4, 6, 3
Row 3: 2, 1, 4, 6, 3, 5
Row 4: 3, 5, 6, 1, 4, 2
Row 5: 4, 3, 1, 5, 2, 6
Row 6: 5, 6, 2, 3, 1, 4

This layout emerges naturally from the careful elimination and placement sequence described, always respecting the puzzle’s core rules of unique digits per row, column, and 2x3 region.

This walkthrough emphasizes logical deduction over guesswork, showcasing the elegance and challenge of solving a 6x6 Sudoku puzzle like LinkedIn Mini Sudoku #121 (Ten).