Google has added a 34 button scientific calculator to the search. Previously used to display just the result when you enter some calculation in the search box. But now it shows a scientific calculator above the search results.
The scientific calculator added today is not only works on PC browsers but also on mobile browsers. You can also use voice search to perform calculations. It works on mobile devices also, atleast it works on Chrome for iOS, but you need to pronounce clearly for it to recognize the voice. On mobile devices flip the phone to landscape mode to see the full calculator.
The calculator includes functions like sines, cosines, tangents etc along with the normal functions. So next time you want to do a complex calculation you can just enter the same in Google instead of searching for a calculator.