1. If there is a significant variation in the price and quantity of food and beverages ordered by people in the group, is it still fair to divide the cost of the check evenly?
2. If a birthday celebrant invites people over for dinner in a restaurant, is he responsible for the bill because he's hosting, or should the group pay for the birthday person's share?
3. Split the check, yes or no?
4. Is it gauche to use a calculator?
1. It's a question of fairness versus ease. If there is a wide variation in socioeconomic status in the group (e.g., mix of graduate students and financial analysts) , I think fairness trumps inconvenience and people should pay what they ate and drank. Otherwise, split the cost evenly.
2. Treat the birthday person.
3. Ask the server at the first opportunity if it's all right to split the check. Otherwise, see #1.
4. The use of technology itself is neutral, but it is the sentiment behind using the calculator that may be considered boorish. I don't think it's boorish to want to pay only for what you consumed. I'm tempted to mention a few anecdotes when I was a starving grad student, but I'll spare you.