Two math professors were having dinner. One complained, "The average person is a mathematical idiot -- he cannot do arithmetic, cannot balance a checkbook, cannot calculate a tip, cannot do percents, …" The other disagreed: "You’re exaggerating. Most people know all the math they need to know."

When the complainer went to the men’s room, the other beckoned the waitress to his table. "The next time you come past our table," he said, "I will ask you a question. I want you to answer by saying 'X squared.'” She agreed. When the other mathematician returned, his companion said, ‘Look, I’ll stop the next person who passes our table and ask him or her an elementary calculus question. I bet he or she can solve it." Soon the waitress came by and he asked: "Excuse me, Miss, but can you tell me the integral of 2x with respect to x?" The waitress replied: "X squared." The mathematician said, "See!" His friend said, "Oh … I guess you were right." And the waitress said, "Plus a constant."