b00gz

I have a zip code function that returns a zipcode and if the zipcode starts with a 0 it chops the 0 off of the front. I integrated this into someone else's system and am not sure how to force the 0 on the front to stay I am using number ranges when I do this for example... If your zip code is between 00000 and 00300 then your cost is $20 and if it is between 00301 and 03000 then its $30. If anyone knows how to force the 0 please let me know. Thanks, Eric