The purple highlighted column is missing the number 2. The red highlighted 2 eliminates
all but one of the empty tiles in this column. The remaining empty tile must be a 2.
Step 14
Simple Elimination
The purple highlighted square is missing the number 2. All but one of the empty tiles
are eliminated by the red highlighted 2. The remaining tile must be a 2.
Step 15
Simple Elimination
There are three empty tiles in the purple highlighted square. One of them has to be a 1.
Two of them are eliminated by the highlighted 1's. The remaining tile must be a 1.