Where is the enter key on I pad

Zip Codes are numbers. Why do you need an enter key?

On the onscreen keyboard the enter key is the large one on the right side of the keyboard.

on a physical keyboard its the one that says “Return”.

The large one the red arrow in the image above is pointing to. Or the one that says return, or the one with the return arrow on it. On the onscreen keyboard the key changes depending on the selected language.