A guy asking for your number isn't flirting, he's asking you out!
Some of my experiences:
Once in a grocery store a woman crashed her cart into mine. She had smiled a lot and made way too much eye contact as we pushed carts around. We met too many times on too many aisles for it to be coincidence. At one point she asked where some common food item was located and I said it was a few aisles over. Later came the crash. She apologized and asked outright if I had a girlfriend. I lied and said yes. Of course you do, she said. Then she asked if I was happy with my girlfriend! Again I lied and said yes. Is she nice? she asked. Yes, I replied. Then she lowered to a whisper: I'm nice, too. Talk about eye-rolling.
Another time in a grocery store a woman stopped me and asked me to reach something on the top shelf for her but wouldn't move out of the way even when I asked her to do so. As I stood to one side and reached over to grab the item she shifted a bit closer to me. Wow you smell really good, she said. I handed her the item and started to move on, but she asked what I thought of it. I haven't tried it, I replied, still moving. She held the box out to me and said, You know what, I've changed my mind. Will you put it back? When I did she moved so close our bodies brushed. Creepy.
Another time I was pushing a cart with my then girlfriend when another woman came right up and started a conversation with me, blocking our way. Her eyes and conversation were focused only on me. My girlfriend, unacknowledged, understood instantly what was going on and said sharply, Excuse me, my boyfriend and I have shopping to do! and almost hit the woman with our cart. Epic fail.
Those three are just a small sample from groceries over the years. Add workplace and social events and myriad other life places and the flirt fails pile up.