In preparation of updating a service pack 1 or possibly cumulative updates, I wanted to verify my farm deployment version.  There are many ways to do this so I will list the ones I know below.

Using PowerShell –

Go to SharePoint 2013 Management Shell

Enter the following script to get the SharePoint 2013 farm build version: (get-spfarm).buildversion

Another method to use is Central Administration

Open SharePoint @013 Central Administration

Enter Upgrade and Migration

From here select Check Product and patch installation status which will displace the build info about all the installed product in your SharePoint 2013 farm environment.