There is so many ways to write your address I always assume it it’s just the house number as well. In fact I vaguely remember that being a specific field when interacting with some old payment gateway.

At American gas stations, if you have a Canadian credit card, you type in 00000 because Canadians don't have ZIP codes.

Funny thing about house numbers: they have their own validation problems. For a while I lived in a building whose house number was of the form 123½ and that was an ongoing source of problems. If it just truncated the ½ that was basically fine (the house at 123 didn't have apartment numbers and the postal workers would deliver it correctly) but validating in online forms (twenty-ish years ago) was a challenge. If they ran any validation at all they'd reject the ½, but it was a crapshoot whether which of "123-1/2" or "123 1/2" would work, or sometimes neither one. The USPS's official recommendation at the time was to enter it as "123 1 2 N Streetname" which usually validated but looked so odd it was my last choice (and some validators rejected the "three numbers" format too).

I don't think I ever tried "123.5", actually.