How in the heck are production Mods calculated?!?

[Talenn]

I'm sure this has been asked before, but I cant find the topic, so here goes...

How are the final values for what each planet produces derived? Using any form of math, I can rarely come up with the exact numbers it is displaying for the a Planet's Mineral/Organics/Radioactives etc.

I've tried summing the bonuses, multiplying it out, forwards, backwards etc. I usually arrive at a number close to the displayed figure, but rarely dead on.

Intuitive method:

Base number for a Mining Facility (say 800)xMineral Modifier for the Planet
xCultural Modifier
xRacial Trait Modifier
xPop Bonus
xHappiness Bonus
=NOT THE NUMBER DISPLAYED...or very rarely.

I cant think of any other modifiers that I could be missing. Could someone please show me how this is all calculated out?

Thanx!
Talenn