How can I increment a number in a while-loop while preserving leading zeroes (BASH < V4)

Question

I am trying to write a BASH script that downloads some transcripts of a podcast with cURL. All transcript files have a name that only differs by three digits: filename

Answer 1

Will this do?

#!/bin/bash

i=1
zi=000000000$i
s=${zi:(-3)}
echo $s