Alphanumeric numbering in Adobe Acrobat X

Hello,

I would like to add alphanumeric pagination.

Basically I need to do add a 3 digit number ending with a letter. So for example: 240a, 240b, 240c etc. I'm using the bates numbering option to this end, however I am unable to get the result I require. I am using a version of Adobe Acrobat X, unfortunately i'm not presently in the office, and hence I'm unsure exactly what version. I assume one of the last prior to DC I follow the usual bates numbering system adding (A) in the suffix box, but that just results with 240a running continuously throughout all the pages. I assume that I need to edit the code that's applied when I select insert bates numbering to hard code what I require. But I don't know what that edit should be. I've tried multiple variations, but have not been able to find a solution. My alternative has been to do each page individually, which is taking for ever as I have multiple documents to prepare this way - there most be a better option.

So in summary, using only Adobe Acrobat. I need to apply alphanumeric numbering as seen in the example above.

I would appreciate if any solutions to can be explained step by step to avoid any confusion on my side when trying to implement the process.

Kind regards

Mike