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

But spotlight replaces alt+space so you can’t minimise or move a window from the command line :(

You meant Microsoft's PowerToys Run, correct?

Spotlight is Mac-only and uses Command-Space by default.

As the sibling comment mentioned, you can customize the keyboard shortcut so you don’t lose alt-space.

If you mean "PowerToys Run", you can reconfigure pretty much any if the PowerToys shortcut key combinations.

Though for now I've just turned that one off as I don't have obvious need for it and haven't looked at what else it might offer. I use PowerToys mainly for FancyZones and plain text paste.