The case notes
How a region sum line works
Each box segment of a region sum line has the same total. Watch a worked example, then try the idea in a puzzle.
Put it into practice
Each box segment has one total
This line crosses a box border. On a region sum line, each part inside a box must add to the same total.
4 + 5 + 6 = 15
The first segment has three cells: four, five and six. They add to fifteen. Keep that total in mind as the line enters the next box.
7 + 8 = 15
The second segment needs fifteen too, even though it has only two cells. One is seven. The other must be eight.
Same sum. Different lengths.
The segments can have different lengths. It is their sums, cut by the box borders, that must match.
Read the transcript
This line crosses a box border. On a region sum line, each part inside a box must add to the same total. The first segment has three cells: four, five and six. They add to fifteen. Keep that total in mind as the line enters the next box. The second segment needs fifteen too, even though it has only two cells. One is seven. The other must be eight. The segments can have different lengths. It is their sums, cut by the box borders, that must match.
