Steps 19-21
| Step 19 | ||
 |
Single Possibility The purple highlighted column is only missing one tile. The missing number is 1, so the empty tile must be a 1. |
 |
| Step 20 | ||
 |
Simple Elimination The purple highlighted row is missing two tiles. One of the missing numbers is 7. The red highlighted 7 eliminates one of the empty tiles, the other empty tile must be a 7. |
 |
| Step 21 | ||
 |
Single Possibility The highlighted row only has one empty tile. That tile must be the missing number, 5. |
 |