Is there a mathematical way to figure out a bikes displacement?

I've always seen bore and stroke figures side-by-side with displacement , does this figure into it? For example the new Ducati 1098 has a bore x stroke figures of 104.0 x 64.7 mm, and a displacement of 1099cc, just wondering how they determine the displacment... any help, or a formula would be great, THANKS!Haha, I know you can"Just look at the side of the bike..."but thanks, that's the smartass type of answer I would have given too...