I think they mean calculation from the start menu search (on a default installation, it will Bing the calculation and show the search result, which I find absurd since it requires an internet connection to solve x+y). The calculator program still works fine offline, but is often overkill when you just want to quickly solve something
I'll note that Microsoft's PowerToys run solves this properly, just like MacOS's Spotlight and the built in search on most Linux desktops