I had dinner tonight with a friend at an Italian restaurant we both like. After we ordered, the waitress brought over a basket of bread and butter. I was starving, and know their bread is very good, but when I went to grab a piece, I noticed there were three pieces in the basket.
This has happened in several other restaurants -- sometimes it's bread, sometimes it's rolls -- and I always wonder, why would you do that? You can clearly see there are two of us at the table. You didn't leave an odd plate and silverware. Bringing us three pieces of bread means we're going to have that awkward moment where we've each consumed one and have to ask, "Are you gonna eat the last one?" Either that, or be flat out rude and grab it quickly and make the other guy look around for the waitress to ask for more.
I know Americans are horrible at math, but this shouldn't be that tough. There needn't be any fractions or prime numbers involved. Simply multiply the number of people at the table by two, and put that many pieces of bread in the basket. Repeat until no one asks for any more.