Incremant integer with leading zero

i want to count how many leading zero user key in, how to do this?
i have 2 textbox to key in, first one integer only, let;s ketin 10
second user can key in 01 or 1, if  01 i need to increment it 10 times (based on first text box)
the value will be 01, 02 ....10
if key in 002
the value will be 001, 002 ... 010.
 
What's the simplest way to do this?
 
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