I recently installed a new version of Windows 10 and noticed that Windows Calculator interface has changed dramatically.
I personally didn't like. It took me a while to figure out how to perform inverse trignometric functions.
Finally, I realized their buttons only show up when the window size is wide enough!
So I decided to restore the classic Calcualtor app. If would like the classic Calculator interface back,
you will need copy the classic Windows Calculator files from an earlier version of Windows 10, or from Windows 7 (this works too).
I attached the needed files to this post. If you don't trust these, you have no choice but to get them manually.