The case notes
How German Whisper lines work
Adjacent digits along a green line differ by at least five. Watch a worked example, then try the idea in a puzzle.
Put it into practice
Neighbours stay five apart
A green line is a German Whisper. Along that line, neighbouring digits must differ by at least five.
From 2: 7, 8 or 9
The first end is two. A cell next to two on this line must be seven, eight or nine.
3 rules out 7
The other end is three. Seven is only four away from three, so it fails. Eight or nine works with both ends.
The row leaves 8
Now ordinary Sudoku joins in. Nine is already in this row. That removes nine, and the middle of the line is eight.
Only adjacent line cells
Check each pair of neighbours on the green line. The two ends do not touch, so they do not need to be five apart.
Read the transcript
A green line is a German Whisper. Along that line, neighbouring digits must differ by at least five. The first end is two. A cell next to two on this line must be seven, eight or nine. The other end is three. Seven is only four away from three, so it fails. Eight or nine works with both ends. Now ordinary Sudoku joins in. Nine is already in this row. That removes nine, and the middle of the line is eight. Check each pair of neighbours on the green line. The two ends do not touch, so they do not need to be five apart.
Keep following the clues
- Kropki Sudoku: Carry a Whisper’s side through a black dot →
- Kropki Sudoku: Let a Whisper choose between dot-chain options →
- German whisper Sudoku: Count low and high digits around a Whisper line →
- German whisper Sudoku: Join two Whisper colour patterns where they meet →
- German whisper Sudoku: Test a candidate through meeting Whisper lines →
