That makes sense if you are counting but i prefer a description. If you are in a building with only one floor, you are at the first floor. There is no such thing as the zeroth floor. Because it is the first floor you see and grasp its existence. Its the first thing you see. There is no such thing as the zeroth. Zero implies nonexistence. You cannot use it when you are counting things that exist. Another example: ln a race there is first, second and third. Who would the zeroth refer to? It would have to refer to the last person who has crossed the line without participating in the race. He might have crossed the line before the first but he does not exist in the race so he does not get a reward.