THREES IN LINE

 

Threes in Line

When two 3s are in line either horizontally or vertically, then four surrounding cells can be solved immediately. This is stated without proof, but a small amount of doodling with pencil and paper will quickly convince you of the truth of the matter.

The second graphic shows the situation after this hint has been acted upon.


 

This is a natural extension of the case shown above. If there are one or more intervening 2s between the in-line 3s there are still four surrounding cells which can be solved immediately. Use paper and pencil again to convince yourself of this.

The second graphic shows the situation after this hint has been acted upon.