In this task, you're given passages that contain mentions of the quantity of a particular object and are supposed to find out the answer for a given question. Craft one correct answer to the question given in input. Make sure your correct answer is consistent with the context, and properly gives the exact number relating to the query.
 In your answer, use as few words as possible from the given context. To be less repetitive, please vary your language for each question.

Sentence: The library system also includes branch libraries for Architecture, Chemistry & Physics, Engineering, Law, and Mathematics as well as information centers in the Mendoza College of Business, the Kellogg Institute for International Studies, the Joan B. Kroc Institute for International Peace Studies, and a slide library in O'Shaughnessy Hall. A theology library was also opened in fall of 2015. Located on the first floor of Stanford Hall, it is the first branch of the library system to be housed in a dorm room. The library system holds over three million volumes, was the single largest university library in the world upon its completion, and remains one of the 100 largest libraries in the country. 
Question: How many books are held by the Notre Dame libraries?
over three million volumes

Sentence: As of 2013, the global advertising agencies of Omnicom Group and Interpublic Group, both based in Manhattan, had combined annual revenues of approximately US$21 billion, reflecting New York City's role as the top global center for the advertising industry, which is metonymously referred to as "Madison Avenue". The city's fashion industry provides approximately 180,000 employees with $11 billion in annual wages. 
Question: About how many people work in the New York fashion industry?
180,000

Sentence: Chopin's output as a composer throughout this period declined in quantity year by year. Whereas in 1841 he had written a dozen works, only six were written in 1842 and six shorter pieces in 1843. In 1844 he wrote only the Op. 58 sonata. 1845 saw the completion of three mazurkas (Op. 59). Although these works were more refined than many of his earlier compositions, Zamoyski opines that "his powers of concentration were failing and his inspiration was beset by anguish, both emotional and intellectual." 
Question: How many pieces did Chopin compose in 1842?

six