LinkedIn Sudoku #428: Pro-Tips for a Fast Solve

The Speed-Run Plan

LinkedIn 6x6 Sudoku #428 uses digits 1 through 6, with each row, column, and 3x2 box requiring one copy of every digit. The fastest route is not random scanning. Start where the clues are concentrated, then let each placement reduce several units at once.

Pro-Tips for #428

1. Cross-Hatch the opening clues

Begin with the upper-left box. Its visible clues are 4 in the second row and 6 in the third, while the first column already contains 6 and 1. Cross-hatching those restrictions quickly limits the missing digits. The early useful placements are not always naked singles, but they establish strong lanes for the next scan.

Repeat the same process through the upper-middle box, where 2, 1, 3, and 5 are already active. The missing values are forced into only a few cells, and the second row becomes especially informative.

2. Watch Row 2 for a hidden single

Row 2 contains 4 and 3, so it must place 1, 2, 5, and 6. Column and box restrictions squeeze 1 into the second position, producing the first clean hidden single of the run. Once that square is fixed, the row's remaining candidates collapse rapidly.

This is the key distinction between a casual solve and a speed-run: do not wait for a cell to show one candidate. Scan the missing digits and ask where each digit can go. That is the hidden-single habit.

3. The crucial square: Row 3, Column 4

The breakthrough comes in the third row. With 6, 5, and 2 already placed, the row is missing 1, 3, and 4. The upper-middle box and column 4 eliminate the alternatives, leaving 1 at Row 3, Column 4.

That is the crucial square. It completes the column's structure enough to trigger a chain through the lower boxes. From there, the third row resolves to 6 3 5 1 4 2, and its newly placed 4 constrains the right side of the grid.

4. Let the bottom-left box do the heavy lifting

The lower-left box contains 1 and 2, so it needs 3, 4, 5, and 6. Column restrictions place 4 and 6 with very little freedom. Once those positions are fixed, the box gives up its remaining values without guessing.

This is where the puzzle feels easier than it looked. A 6x6 grid has fewer candidates per unit, so one resolved box can affect four rows and columns immediately.

5. Finish through the difficult row

Row 5 is the difficult row because its opening clue, 2, sits beside a sparse field. Do not attack it in isolation. Use the completed lower-left box and the right-side columns first. They reduce the row to a tight sequence, placing 4 early and leaving 6, 5, 3, and 1 to fall into place.

Once Row 5 resolves as 4 2 6 5 3 1, the final row is nearly automatic. Its existing 1 and 4 combine with the column checks to produce 3 5 1 4 2 6.

Final Check

The completed grid is:

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

Every row, column, and 3x2 box contains digits 1 through 6 exactly once. The clean solving line is cross-hatching first, hidden singles in the upper bands, then the Row 3 Column 4 breakthrough. That is the tactical route through #428, with no guesswork required.