Does giving a guy/ man your number without him asking for it
I think, as some people have already said on here, the main thing you've learnt is how that guy interprets the situation.
This is one of the reasons why I hate all these unspoken social rules, which don't really make sense. Context is always a factor with these things and I think this is another area where having AS adds to the problem. For me I feel that AS makes it harder for NTs to read us as we just don't naturally give out these "signals", so in this example, if the guy is unsure what your interest level in him is, he will probably read more into you giving him your number than what is intended.
So in summary I don't believe a girl giving a guy her number means she is interested, but unfortunately (and it's worse if you are AS) as it's a break from the social norm of the guy taking the lead in these situations, it is more likely to be taken as a sign of affection than anything else.
Sometimes I wonder if I miss out on these opportunities where someone left me a note but I simply never saw it. I'm usually a space cadet, or spaced out. How does one even say that? Anyway, I miss so many sensory details that I'm beginning to think that people are actually interested, but I just can't "see" it or notice it. It would really help, if they just take the note and stick it in my hand and say. "HERE! READ IT LATER" but alas, nobody wants to do that because everyone is so damn afraid of being exposed and rejected in public. So even NTs are afraid of being humiliated. Silly human beings, social constructs just doesn't gel with me. Why? Well because it makes sense today, in this location, but tomorrow in another location/country/culture it makes no sense. Oh well. Maybe I should wear a sign board around my neck that reads "BE DIRECT".