instruction: For 542 , how many times has Prof. Pelham Barron taught ?
response: SELECT COUNT(*) FROM course, course_offering, instructor, offering_instructor WHERE course.course_id = course_offering.course_id AND course.number = 542 AND instructor.name LIKE '%Pelham Barron%' AND offering_instructor.instructor_id = instructor.instructor_id AND offering_instructor.offering_id = course_offering.offering_id