With all the various synergies and side effects buildings can have, it is difficult to track what the actual marginal value of each building is in terms of cookie production rate. The way I usually do this is to look at the production rate before and after buying a building and take the difference. The problem comes in when using short numbers (which I prefer), in particular if your production has just crossed a power of 1,000 boundary, you lose a lot of information, and for some buildings, you can't see the effect they're having on production rate. Instead of 3 decimal places, it would be better if short numbers were formatted to provide 6 significant figures, regardless of how many decimals that is. Alternatively, you could just have the interface show the actual marginal value of each building, taking into account whatever synergies and other modifiers were in effect.