Formating Dates

Hello,

I am trying to do a VLookup between to spread sheets and having a terrible time with the dates formatting correctly. Each spread sheet comes from a different program and put into excel one file is opened with a delimited format and the other is not. My problem is on one spread sheet the date shows as 06/27/2013 and in the delimited spread sheet is shows as 20130627. Can you tell me how I can format these so when doing our compare this will work.
Thank you,