The last missing digit is the easiest pattern to spot in Sudoku.
Understanding the Concept
When a row, column, or box has 8 numbers filled, only one digit is missing.
Simply identify which number from 1-9 isn't present.
This technique is also called "Last Free Cell" or "Single Empty Cell".
It's the most basic solving technique and requires no complex logic.
Always scan for these easy wins before using harder techniques.
In easy puzzles, you can often solve many cells using just this technique.
Examples
Row Example
If a row contains 1,2,3,4,5,6,7,9, then the missing digit is 8.
Box Example
If a box has eight numbers filled, quickly spot the missing ninth number.
Pro Tips
- •Scan all rows, columns, and boxes for this pattern
- •This should always be your first technique to try
- •Easy puzzles have many last missing digit opportunities
- •Check again after placing each number - new opportunities appear
