The digits in the grey cells are part of a domino of which the sum of both digits adds to a prime number.
Solve online in Penpa+ (thx Nick Smirnov!)
Link to the first Prime Domino.
Solution code: The missing digits, row by row.
on 9. October 2022, 07:55 by Richard
Added link and tag for online solving. Thx Nick!
on 3. October 2022, 19:40 by Nick Smirnov
Penpa:
https://tinyurl.com/2k62r2vm
on 16. August 2013, 21:12 by Statistica
Sehr hübsch. Aber warum die Eins in der ersten Zeile grauen (oder die Drei in der zweiten)? Das sind doch offensichtlich Prim-Dominos!
Please note: The German version of this page has changed. It is possible that this page does not contain the latest information.