Using Excel 2003

We manufacture products that have 4 properties, stored in columns B, C, D
and E. I create a part number for each product by concatenating the data in
the four columns. The property in Column D can be from 1 to 6 characters in
length, so when I create the part number, I apply the following formula to
the data in column D:
RIGHT("00000"&D1,6)
to ensure that all part numbers will be of the same length. When the part
number is created, it is 13 characters long.

What formula can I apply to the part number to extract the original property
in column D, stripping away only the leading zeros?

TIA
David