Unable to convert custom/text column to number

Hello,
I am using a user form I created to copy CSV files to a macro enabled workbook. The user picks from a drop down list of about 7 tabs and the form appends the data to that tab. That works fine. However, I have 3 columns I need to change to number and add leading zeros. For example, 3 becomes 00003. No matter what code I try, I cannot get this to work and I've tried a large number. The columns in question are B, D, and F. Right now, I'm just trying to get B to convert. This is Excel 2010. Does anyone have any suggestions because I'm pulling my hair out over here?!?

Jeff