how do i zero fill numeric values based on a dynamic number input by the user?

I have a table with string values and numeric values that I need to concatenate together.  The string value should go first then add 0's before the numeric value and concatenate to the string value.

maxbates table contains
prefix      varchar(255)
test

mysqltable contains

batesnum (numeric)    n_batesnum (varchar(255)
12345                          <null>
12346                          <null>
234567                        <null>
234568                        <null>
3456789                      <null>
3456790                      <null>

In a vb app, the user inputs that there should be 8 characters in the batesnum value so the final table
should look like this

mysqltable
batesnum   n_batesnum
12345         test00012345
12346         test00012346
234567       test00234567
234568       test00234568
3456789     test03456789
3456790     test03456790  


Thank you,

amhinkel