German Whispers Sudoku: Rules & How to Solve
Neighbouring digits on the green line must differ by at least 5. A deceptively tight constraint built around the 5.
The rule
Along a German whispers line, every pair of adjacent digits must differ by at least 5. So a 1 can only sit beside a 6, 7, 8, or 9, and a 4 only beside a 9.
German whispers partner table
Adjacent digits along a whispers line must differ by at least 5. Written out, that rule is far more restrictive than it sounds:
| Digit | Legal neighbours on the line |
|---|---|
| 1 | 6, 7, 8, 9 |
| 2 | 7, 8, 9 |
| 3 | 8, 9 |
| 4 | 9 |
| 5 | none — 5 cannot appear on a whispers line |
| 6 | 1 |
| 7 | 1, 2 |
| 8 | 1, 2, 3 |
| 9 | 1, 2, 3, 4 |
Two consequences fall straight out. First, 5 can never appear on a german whispers line — no digit is 5 away from it in either direction. Second, the line must alternate between the low band 1–4 and the high band 6–9, because no two lows and no two highs are ever 5 apart.
VariantDoku shows the same reference inside the app: open any puzzle, tap the rules sheet, and each constraint on the grid gets its own tips card.
How to solve german whispers sudoku
5 can't appear
No digit differs from 5 by 5 or more, so a 5 can never sit on a German whispers line — strike it from every line cell.
Low and high alternate
Because each step jumps by 5+, the line ping-pongs between the low group (1–4) and the high group (6–9).
Endpoints have options
An end cell only has one neighbour to satisfy, so it's less constrained than a middle cell that must clash with both sides.
Rule out 5 immediately
No digit differs from 5 by at least 5, so 5 can never sit on a whispers line. Cross it off every cell on the line before doing anything else.
Alternate the bands
Lows (1–4) and highs (6–9) must alternate along the line. Fix one cell's band and every other cell's band follows.
Step by step: techniques from the hint engine
Each example is drawn the way VariantDoku's hints show it: red candidates are eliminated, blue ones are what the step proves, and green cells are solved.
Lows and highs alternate
Neighbours on a whispers line differ by at least 5, so no digit can neighbour a 5, and two lows (1–4) or two highs (6–9) never touch. Next to a 3 the only partners are 8 and 9. With no second 3 allowed in the row, the far end is low again — 1, 2 or 4 — and 4 survives only if its neighbour turns out to be 9.
No 4 or 6 where a line bends inside a box
4 has exactly one legal neighbour (9) and 6 has exactly one (1). A cell in the middle of a line has two neighbours, so a 4 there would need a 9 on both sides. When those two neighbours share a box, row or column they cannot both be 9, so the middle cell cannot be 4 — and, by the same argument, cannot be 6.
A worked example
Colour the line before you solve it: one colour for lows (1–4), another for highs (6–9). Because the bands strictly alternate, fixing a single cell fixes the band of every other cell on the line.
Then tighten with the table. A 4 on the line can only sit next to 9, so its neighbours are known immediately. A 1 is the loosest digit, accepting 6, 7, 8 or 9. If a whispers line runs through a row that already contains 9, every 4 on that line is in trouble — which is often the crack that opens the puzzle.
On 4×4 and 6×6 boards
VariantDoku's 6×6 puzzles keep the 9×9 rule — neighbours differ by at least 5 — and among 1–6 only 1 and 6 are that far apart. Every cell on a 6×6 whispers line is therefore 1 or 6, alternating along the line, and cells two steps apart hold the same digit, so they can never share a row, column or box. German whispers never appear on 4×4 boards: no two digits from 1–4 differ by 5.
| Board | Legal neighbours |
|---|---|
| 4×4 | none — no two digits are 5 apart |
| 6×6 | 1 → 6 · 6 → 1 |
Try one from the catalog
Real VariantDoku puzzles with this rule. Each one opens in the app.
Frequently asked questions
What is a German whispers line?
A line where consecutive cells must differ by at least 5, such as 1 next to 7.
Can a 5 go on a German whispers line?
No. Nothing differs from 5 by 5 or more, so 5 is impossible anywhere on the line.
How is it different from Dutch whispers?
Dutch whispers require a difference of at least 4; German whispers require at least 5, which forbids the 5 entirely.
Can 5 appear on a german whispers line?
No. 5 has no legal neighbour — the nearest digits 5 away would be 0 or 10, neither of which exists in sudoku.
What digits can sit next to a 4 on a whispers line?
Only 9. Similarly a 6 can only sit next to 1, making 4 and 6 the most restrictive digits on the line.
Play German Whispers Sudoku in VariantDoku
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