Cerenese combination lock

[mini]

Hi all!

I'm playing book 13 for the first time (only 1-12 were ever translated into Swedish), and I'm "stuck" on the combination lock in section 227.

It's totally not obvious to me. In the previous books, the riddles have always had some logic to them, but I just can't find any clue here. Is there a section somewhere that gives a hint? Please help, I'm just too curious :-)

/Mikael

[Ghost Bear]

You have to consider each row, column and diagonal as a whole, rather than concentrate on individual numbers.

Or, if you just want the spoiler:

Add up each row, column and diagonal. They all total 15

[mini]

*Blush*

Oh, that was way too easy for me to see.

Thanks!