On the Auto Number, allow users to select the format or perhaps the start from number, or number of digits. For Instance “Start from 1000” or “Start from 10000”. This way, you can have a standard number of digits to start from, so you don’t have one with one digits, another with 2 digits, another with 3 digits, and so forth.
This was slightly problematic for me personally last year when judges were entering score and for instance searching an entry “52” and it pulled up entry “352”.