Strategy Detailed Descriptions

Simple Strategies

Intersecting groups allow that only 1 cell in a group can contain a certain number

For a certain number, look for a box, row, or column has only one cell that can contain a certain number. Where this number is in an intersecting group, those cells that intersect cannot contain that number. Find where only one cell is left as a possibility.

Note in the example below that the upper left cell * in the first box is the only one that can contain a 4:

In the following example, only the 4^th cell * in the top row can contain a 4:

Next: Intersecting groups with an additional row or column excluded