Precision errors are common, but usually inconsequential. Remember that the decimal values are being translated to binary and there are limits to how much overhead programmers want to take on. I wouldn't worry about it. In the real world accuracy past 4 to 5 places is rarely needed and past 11 is pretty much unknown.
Ignacio wrote: OS X.3.# you go to the Calculator, type 200000 * 1.12 and get 224000.
OS X.4, same thing, you get a weird 224000.000000000029.
It's a known problem with the Calculator in OSX.4. I think there was another one of the same kind in OSX.3, but I don't remember the figures. It's not a hardware or system problem. Therefore, other calculators work.
I guess Apple don't think people use the Calculator much. At least not enough to give thsi problem enough priority. I think it's embarrassing for them.