I will never understand why some people feel the need to include the preposition “at” after asking about someone’s whereabouts. If you ask where they are, is that not sufficient? Adding a preposition to the end of the statement or question only makes it a more lengthy response. Simply asking where someone is should get the point across. Adding the extra, unnecessary word “at” after posing a query about the location of one does nothing to further clarify what is being questioned.