Who hasn't been that guy doing mental math on a $14 plate of nachos while everyone else just wants to eat? I'm usually the cheap one in the group, so I feel this in my soul. One time I caught myself counting chips like a total weirdo and had to stop and ask what I was even doing with my life. Splitting by head count only works if everyone eats the same amount, and nobody ever does. The real move is order more than enough and just split it even, then nobody has to play accountant. It costs you a couple bucks at most and saves you a friendship.