Batch renaming files should be one of the easiest operations to perform in the Mac file system, yet it is seemingly a non-existent feature. Thankfully, there is an easy way to enable this service.
It really is quite easy to do via Mac's "Automator" App that comes with every Mac.
To start, open the Automator App and select "Service" on the initial pop-up choice list.
After this, you can add any number of automated services. For our project, in the left-hand column under "library" choose "Files and Folders." Now a second column will appear with more choices. From this list, drag and drop "Get selected Finder Items" to the main workspace. Follow this with the "Rename Finder Items" option.
Rather than try to walk you through each step, let me show you a screen shot of the options you should change: