Helmet design is always the easiest way to identify, until they start change every few races....
Or their both the same colour.
Seriously, why the hell is deuse putting so much effort into arguing against simply sticking the car number on the rear wing end fence? Oh wait no, its deuse..
The yellow on the camera is on the leading edge, its not easily visible from side on. Neither is most of the drivers helmet due to the side impact protection. So from side on its genuinely difficult to see which car is which while trackside. You can't see the number on the nose from the side.
Sticking the number on the rear wing end fence is such a blatantly obvious thing to do, as pretty much every other single seater series that had wings does it. But F1 teams refuse as they want to sell the space, and the FIA don't do anything about it. And then half the end fences are blank anyway!
a two digit screen? lets look at the number 10
goma
kudhan
toban
mute
عَشَرة
għaxra
and so on https://en.wikipedia.org/wiki/List_of_numbers_in_various_languages
I've literally no idea what your chatting about?