When you need to parse a number, the first instinct is often to convert it to a string and slice it. That works well for data that comes from people — like phone numbers, credit cards, or postal codes — where formatting and leading zeros matter. But when you are working with raw numeric data that is guaranteed to be fixed-width and free of formatting, numeric parsing with integer division (//) and modulus (%) is the better option.
String parsing is flexible, but numeric parsing is faster and cleaner when the data is truly numeric.