LinkedIn Mini Sudoku uses the digits 1 to 6. Every row, column and shaded region must contain each digit exactly once. Use the region boundaries displayed on the board. A number that fits its row can still be excluded by its column or region.
Compute a cell's candidates
A candidate survives all three constraints at once. Start with the missing digits in the row, remove digits already present in the column, and then remove those already present in the region. The order of those checks does not change the result.
Digits missing from row: {2, 5}
Digits missing from column: {1, 2, 4}
Digits missing from region: {2, 3, 5}
Allowed in this cell: {2}This is a naked single: only one candidate remains in the cell. The example does not specify a complete board. It demonstrates the set operation that justifies a placement, which you can apply to any cell on the actual grid.
Look for a digit with only one home
A hidden single is different. Several digits may remain possible in one cell, but a particular digit has no other position in its row, column or region. Suppose a row's three empty cells have candidates {2,5}, {2,4} and {2,4}. Only the first can contain 5, so it must be 5. The other candidates in that cell do not prevent this deduction.
Scan one digit at a time when a row-by-row search stops helping. Find where that digit already appears and eliminate its row and column from each region still missing it. A single surviving position is a placement; two surviving positions are useful notes but do not yet choose a square.
Use pairs only within the same unit
If two empty cells in one row each have exactly {2,5}, they must consume 2 and 5 in some order. Remove 2 and 5 from other candidate sets in that row. The same applies within a column or a region.
Two cells in unrelated parts of the board do not form a useful pair merely because their notes match. Also check that the candidate sets really are complete: if one cell also permits 6, the two-digit pair has not been established.
Follow a region-to-row restriction
Suppose all possible positions for digit 4 in one region lie in its top row. That region's 4 must be placed somewhere in that row, so no cell outside the region in the same row can be 4. You still cannot choose between the region's unresolved candidates.
The reverse restriction also works: if all positions for a row's 4 lie inside one region, remove 4 from the other cells of that region. Name the digit and the shared unit before crossing out a candidate. This makes the logic easier to check later.
Keep notes synchronized
After placing a digit, update the affected row, column and region. Stale notes create false pairs and hide singles. If a cell has no candidates left, at least one earlier placement or exclusion was wrong. Recheck the most recent change instead of entering a value that is already ruled out.
Use the game's notes and highlight features to reduce bookkeeping. A hint is most useful after you can describe the bottleneck: a missed single, a region interaction or a mistaken candidate. That lets you learn a deduction from the hint rather than simply copying a digit.
Validate the whole result
Check all rows, all columns and all regions separately. A completed row containing 1 to 6 does not establish the rest of the board. During practice, save one deduction in plain words, such as “5 has only one position in this region.” That is more transferable than memorizing the final grid.
Rules and controls: LinkedIn Help: playing Mini Sudoku. These examples are instructional exercises, separate from the current daily puzzle.
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