I’ve found myself needing to know which version(s) of the .NET are installed on a server and the easiest way I’ve discovered is to browse to the directory and check the version on mscor*.dll files.
Browse to this directory which is the same on all versions of Windows currently in use.
Go into the Framework or Framework64 directories and you’ll see the overview of versions installed. For example, you might have a directory called v4.0.30319 and you would be forgiven for thinking that is the version installed. But what if you know you have .NET 4.5 or even 4.7 installed?
You can go into the directory and find the DLLs whose name begins mscor then right-click -> Properties -> Details tab and see the file version. This matches the version of .NET.