There is a couple of ways to do it:

• If you reference the dll in Visual Studio right click it (in ProjectName/References folder) and select "Properties" you have "Version" and "Runtime Version" there.

• In File Explorer when you right click the dll file and select properties there is a "File Version" and "Product Version" there.

• Alternatively, investigate it in code:

  Assembly assembly = Assembly.LoadFrom("TestAssembly.dll");
  Version ver = assembly.GetName().Version;