Logic Grid Tips & Strategy

Logic grids are solved by elimination, not inspiration. The method below solves easy and medium grids without a single guess.

1. Start with the fullest rows, columns and boxes

Pick the row, column or box with the most numbers already in it. The fewer empty cells, the fewer candidates each one has — and the more likely one of them has only one possible number.

2. Hunt for hidden singles

For each empty cell, list the numbers that could still go there (not already in its row, column or box). If exactly one number fits, it must go there. These "naked singles" are the engine of every solve: fill them first, and new singles appear.

3. Cross-check the other direction

Instead of asking "what fits in this cell?", ask "where can this number go in this box?" If a number fits in only one cell of a box, it goes there even if that cell had other candidates.

4. Slow down on 9×9

On the big grid, resist the urge to fill quickly. A wrong entry costs one of only three mistakes. When stuck, switch to a different region — progress elsewhere often unlocks the cell you were staring at.

5. Use hints as a diagnostic

A hint fills a cell correctly. If you are truly stuck, take one hint and ask why that number had to go there — the answer usually unblocks two or three more cells.