When I search for "4 inches in g" on my Windows Firefox I immediately get a unit conversion done by Google that shows up before the actual search results. On my Ubuntu 12.04 system this does not work though. I tried Firefox and Chromium and have no script blockers installed. I also switched off AdBlock Plus for testing but to no avail.

I realize that this is not really Ubuntu doing something wrong but:

Are there any settings I can modify to make Google show these results?

I use them quite frequently and I believe (though I cannot test it anymore) that this used to work on my last Ubuntu System. Maybe there are some script sources that Ubuntu has disabled by default or something like that?