The Windows 10 Calculator is a Store app, and Server 2016 LTSB doesn't include Store apps. Therefore, Server 2016 LTSB doesn't have Calculator.
While I guess they could bundle the Windows 7/8 Calculator with Server 2016, that would make server and desktop Windows different (for a feature that both include).
While I guess they could bundle the Windows 7/8 Calculator with Server 2016, that would make server and desktop Windows different (for a feature that both include).
To make another guess, a lot of Server/LTSB users might actually like an even older Calculator:
They don't even include the Edge browser on Windows 10 LTSB. That's ... strange. Edge has been out for like 18 months on Windows 10. They really seem to have taken out the whole UWP platform on LTSB, so we once again see that the whole "one Windows to rule them all" spiel is nothing but a nice marketing story Microsoft likes to tell its fans, but not as real as they might like it to be. Unfortunately this just means Internet Explorer will have to be supported that much longer by developers.
Good advice in general for almost any software.