LinkedIn 6x6 Sudoku #345: Pro-Tips Guide

LinkedIn 6x6 Sudoku #345: the speed-run setup

This one is a classic LinkedIn mini Sudoku: a 6x6 grid with 2x3 boxes, where every row, column, and box must contain 1 through 6 exactly once. The solve is not about brute force, it is about finding the first place where the grid stops being flexible and starts being forced.

For #345, the board gives you a very clean runway. The opening is built around the already-seeded center-left structure, and the puzzle cracks when you stop treating each empty square as separate and start reading the grid as a set of intersecting restraints.

The key idea: work the most constrained number first

The fastest way through a 6x6 is to scan for the digit that already has the most pressure on it. In this puzzle, the heavy lifting comes from the numbers that already appear multiple times in the middle rows and columns. That makes a number like 6 especially useful as an anchor, because its possible homes get chopped down quickly by row, column, and box conflicts.

Instead of asking, "What fits in this square?", ask, "Where can this digit still go?" That shift is what turns a slow grind into a clean solve.

The Crucial Square

The puzzle really opens when you lock down the top-left corner of the grid. That square is the kind of Crucial Square veteran solvers love because it sits at the intersection of two tightly controlled structures: the first row and the first 2x3 box. Once that corner is forced, the rest of the top band stops being mysterious and starts becoming a chain reaction.

That is the moment to stop wandering. Once the top-left corner is identified, the surrounding row and box collapse into near-singletons, and the solution begins to cascade.

How the solve unfolds

The first real breakthrough comes from cross-hatching. In a 6x6, that means tracing a digit through its row and box at the same time until only one landing spot survives. Here, the top-left box and the first row work together to eliminate almost everything around them. The grid is small enough that one well-placed digit can erase half a dozen possibilities instantly.

After that, the puzzle shifts into hidden singles. These are squares where a number is not obvious at first glance, but becomes mandatory because no other cell in the row, column, or box can take it. In this puzzle, that technique is especially strong in the upper rows and the left-side boxes, where the early placements leave only one legal home for a missing digit.

Why the top rows matter

Rows 1 and 2 are the useful pressure points. Once a few entries are confirmed there, the first 2x3 box stops being a blank canvas and becomes a narrow corridor. That is where the hidden singles reveal themselves. When a row already contains most of its digits, the remaining values are not guessed, they are forced.

Why the middle columns matter

The middle columns are the real traffic lanes in this grid. They intersect both of the top boxes and both of the central boxes, so any digit placed there sends out a strong ripple. In a 6x6, that kind of overlap is gold. It is where you get the most value from each deduction.

Practical pro-tips for this specific grid

• Start with the densest band, not the emptiest one. The center-left structure gives more information than the open corners.
• Use cross-hatching on 6 first. In this puzzle, 6 is one of the best anchor digits because its legal spaces shrink fast.
• Check the top-left box as a unit. Do not solve it cell by cell. In 6x6, a box often yields a forced placement before an individual square does.
• Watch for hidden singles in rows 1 and 2. Once one digit lands, the row usually reveals its last missing number immediately after.
• Look for the domino effect. One placement here often completes a row, which then completes a column, which then clears a box.

The veteran-player pattern

The fastest way to describe this solve is: anchor, cross-hatch, then cash in the hidden singles. That is the whole speed-run. You do not need to chase every empty square. You need one square that collapses the structure, then you ride the forced placements until the board is done.

If you are solving LinkedIn 6x6 Sudoku #345 under time pressure, remember the real trick: the puzzle is not hard because it is large, it is hard because it looks open. Once you find the first truly constrained square, the whole grid stops pretending to be flexible.