How long could I stay in a Barns and Noble?

I feel that I would be able to complete my homework faster if I was in a setting like a Barns and Noble, however I do not want to be kicked out for loitering. If I was to purchase a coffee from the in-store Starbucks do you think they would allow me to work for an hour or two? I realize that this my seem to be a stupid question, however I just fear that I will be seen as loitering.|||Yeah you should be allowed to go in there and work|||No? People go there all the time to do stuff like that. There was a B%26amp;N across the street from my high school, so I'd go there all the time after school and work for hours. I never had any trouble.|||No! Why would they? Barnes and Nobles, Borders, etc are designed to have people come there and work.