Northwestern University:

The four-year, full-time undergraduate program comprises the majority of enrollments at the university and emphasizes instruction in the arts and sciences, plus the professions of engineering, journalism, communication, music, and education. Although a foundation in the liberal arts and sciences is required in all majors, there is no required common core curriculum; individual degree requirements are set by the faculty of each school. Northwestern's full-time undergraduate and graduate programs operate on an approximately 10-week academic quarter system with the academic year beginning in late September and ending in early June. Undergraduates typically take four courses each quarter and twelve courses in an academic year and are required to complete at least twelve quarters on campus to graduate. Northwestern offers honors, accelerated, and joint degree programs in medicine, science, mathematics, engineering, and journalism. The comprehensive doctoral graduate program has high coexistence with undergraduate programs.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". How many quarters are undergraduates required to complete on campus to graduate?
at least twelve