Sudoku strategy - Squeezing

Squeezing utilizes one or two solved numbers in connected boxes to locate the same number in the third connected box. Consider the band (3 horizontally connected boxes) shown above. The number 4 is already solved in the last two boxes. The green color highlights all the squares on which a 4 is not permissible. In the third connected block, only one unsolved square is not highlighted by green, and since that's the only square left, it must be a 4.

The graphic above shows an example of when one solved number is enough to obtain a squeezing solution.