German whisper Sudoku rules and puzzles

The case notes

Count low and high digits around a Whisper line

A German Whisper jumps at least five between neighbours. That makes each step switch between low digits, one to four, and high digits, six to nine. Watch a worked example, then try the idea in a puzzle.

Put it into practice

Low 1–4 · High 6–9

A German Whisper jumps at least five between neighbours. That makes each step switch between low digits, one to four, and high digits, six to nine.

L–H–L or H–L–H?

Across three cells, the line could go low, high, low. Or it could go high, low, high. We can decide which by counting the row.

Three lows already in the row

A full row has exactly four low digits: one, two, three and four. We already have two, three and four outside the line. Only one low place remains.

High · Low · High

Low, high, low would use two more low digits. That is impossible. The ends must be high, and the middle must be the one low cell.

r1c5 = 1

Two, three and four are already used. The only low digit left is one, so put one in the middle. We have solved it without knowing either end.

Read the transcript

A German Whisper jumps at least five between neighbours. That makes each step switch between low digits, one to four, and high digits, six to nine. Across three cells, the line could go low, high, low. Or it could go high, low, high. We can decide which by counting the row. A full row has exactly four low digits: one, two, three and four. We already have two, three and four outside the line. Only one low place remains. Low, high, low would use two more low digits. That is impossible. The ends must be high, and the middle must be the one low cell. Two, three and four are already used. The only low digit left is one, so put one in the middle. We have solved it without knowing either end.

Keep following the clues