How would you add zeros to the beginning of an Integer, such that there are 4 total digits in the number?

zfill or format are not obscure at all.

A python integer cannot have leading zeros. It's simply not possible. zfill and format work with strings. You can also use f-strings to add zeros to a string:

data = 15
print(f"{data:0>4}")

That said this sounds like an XY problem. We could help a lot more if you told us what problem you are trying to solve, not just how you are trying to solve it. What's the big picture here? http://xyproblem.info

This can work:

f=lambda n: '0'*(4-len(str(n)))+str(n)

f(15)='0015'

Basically, just convert to string, find the length, and use that to calculate the number of zeros required. Then use '0'*n to generate that number of zeroes and slap the original number on the end.