The numbers outside the grid are the difference between the highest and the lowest digits in the first three cells from that side.
Solution code: Column 8, followed by row 9.
on 30. April 2022, 12:40 by Nick Smirnov
F-puzzles:
https://f-puzzles.com/?id=y5u8udy7
CTC App:
https://tinyurl.com/4anjea4u
on 9. November 2010, 15:50 by miez
Immer wieder erstaunlich, wie sich alles ergibt... Hat riesig Spaß gemacht!
on 30. September 2010, 20:19 by CHalb
Not easy and this OK is a lot more than just OK. It is surprising and really good.
on 28. September 2010, 23:20 by Rollo
Ganz toll!
on 20. August 2010, 13:31 by Richard
At least, no 'tricks' are involved in this puzzle. Number two does have a few tricks, but not enough to make it impopular. I hope/expect.
But I have to admit that sometimes I am completely lost about the rating of the difficulty.
on 20. August 2010, 13:25 by ibag
Also, leicht fand ich das nicht!