Win7 Batch Convert String To Number

Hi,

I have a folder within which there are multiple subfolders recursively. all these sub folders are named with a timestamp e.g. c:\test\2010112414254234 i.e year(4 chars) month (2 chars) date (2 chars) hour (2 chars) minute (2 chars) second (2chars) millisecond (2 chars). now my batch script needs to go into the root i.e. “test” and delete all folders 1 day (24hrs) older than todays date time, so i need to convert that foldername into an int and do a number comaprision, or is there a better way… thanks for your help…