Database: university
Question: Calculate the number of international students of University of Wisconsin-Madison in 2013.
SQL: SELECT CAST(T1.num_students * T1.pct_international_students AS REAL) / 100 FROM university_year AS T1 INNER JOIN university AS T2 ON T1.university_id = T2.id WHERE T1.year = 2013 AND T2.university_name = 'University of Wisconsin-Madison'