Oh I see, from looking at some examples it's the one without the bar on the bottom? I use the the more French/European '1' to distinguish from a lowercase 'l' (so that C1 does not look like Cl = chlorine).
Yeah the way I originally learned to do it is with no bottom bar and a short, 45ยบ, straight serif. The french way has a lloooooong curving serif, at least as long as the downstroke. Or at least I think of it as french since that's where I ran into it. Maybe that's the norm in europe?