Quickly find out which version of .NET you are on

I had to install WMF 3.0 on one of my Server 2008 R2 machines, a pre-requisite to which is that the machine must have .NET 4.0 (standalone installer here, Server Core installer here). So how do I find whether my machine has .NET 4.0? Simple – there’s a registry key you can check. See this link for more details. Very quickly, in my case, since I only want to see whether .NET 4.0 is present or not, the following command will suffice: 

In my case .NET 4.0 was not installed:

By the way if you try installing WMF 3.0 without .NET 4.0 present, you’ll get an not so helpful error “The update is not applicable to your computer.”