Numeric or Alpha

I am just starting to build a table, i have a RefNo which must always
be 10 numbers long, so I have set the field as numeric.

Some of these RefNo's begin with a "0" or even "00", after i have put
them in the first 0's dissapear. The field is set as numer does this
mean i will have to set the field as text so that the first 0's appear
and hold in place.? or is there something i can do to force the 0 to
stay in place and still keep the field numeric.

I also need to ensure that there are always 10 digits in the RefNo
field, with any missing numbers being shown as 0 at the start of the
number.(sorry i may have asked the same question twice.)

The RefNo field will become very important latter as i had wanted to
use it as the primary key, and it will be used in a lot of search
querys