Scanning: Solving by Eye

How to confirm numbers quickly without notes.

Scanning is a technique for visually tracking where a specific number can go within each line and box. It's worth trying before you start writing notes.

Pick a number, follow every line that already contains it, and in the boxes it crosses, rule out the cells where that number can't go. When only one cell remains, that's a Hidden Single.

Alternating between scanning rows and scanning columns keeps revealing confirmed cells. Scanning alone can solve most Easy and Medium puzzles.