The case notes
How an outside clue works
The digit outside the grid must appear in one of the first three cells of the row from that clue. Watch a worked example, then try the idea in a puzzle.
Put it into practice
Look in the first three cells
An outside clue gives a digit to find near the edge. Read inward from the clue: that digit appears in one of the first three cells.
The 2 is within three cells
Here the outside digit is two. It must be in the first, second or third cell of this row. Cells farther away do not satisfy this clue.
Only the middle cell remains
The first cell is one, and the third is three. Neither can be the outside two. That leaves the middle cell.
The middle cell is 2
Put two here: an outside clue tells you where a digit must appear, not a sum to calculate.
Read the transcript
An outside clue gives a digit to find near the edge. Read inward from the clue: that digit appears in one of the first three cells. Here the outside digit is two. It must be in the first, second or third cell of this row. Cells farther away do not satisfy this clue. The first cell is one, and the third is three. Neither can be the outside two. That leaves the middle cell. Put two here: an outside clue tells you where a digit must appear, not a sum to calculate.
