and full-tuition merit-based scholarships. These factors have propelled USC into being the 4th most economically diverse university in the nation. USC enrolls one of the largest amounts of National Merit Scholars of any university, offering finalists in the program its half-tuition Presidential Scholarship. As of 2021, about 72% of the student body receives about $810 million in financial aid annually. Twenty percent of admitted and attending students are SCions, or students with familial ties to USC, while 14 percent are the first generation in their family to attend any form of college. Twenty-four percent of undergraduates at USC are Pell Grant-eligible, which is defined by having come from a family household income of less than $50,000. There are over 375,000 living Trojan alumni. The USC-MSA reference is a numbering system developed by the Muslim Students' Association of the University of Southern California to access their database of the six major Hadith collections. Although the project currently parked, the referencing remains widely used throughout the Internet. Undergraduate admissions USC is ranked by U.S. News & World Report as "Most Selective," and Princeton Review rates its admissions selectivity of 98 out of 99. Over 70,000 students applied for admission to the undergraduate class entering in 2021, with 12% being admitted. Among enrolled freshman for Fall 2019, the interquartile (middle 50%) range of SAT scores was 670-740 for evidence-based reading and writing, 680-790 for math, and 1370-1520 for the composite. The middle 50% ACT score range was 28-34 for math, 32-35 for English, and 31-34 for the composite. USC was ranked the 10th most applied to university in the nation for fall 2014 by U.S. News & World Report. Faculty and research The university is classified among "R1: Doctoral Universities – Very high research activity". According to the National Science Foundation, USC spent $891 million on research and development in 2018, ranking it 23rd in the nation. USC employs approximately 4,706 full-time faculty, 1,816 part-time faculty, 16,614 staff members, and 4,817 student workers. 350 postdoctoral fellows are supported along with over 800 medical residents. Among the USC faculty, 17 are members of the National Academy of Sciences, 16 are members of the National Academy of Medicine, 37 are members of the National Academy of Engineering, 97 are members of the American Association for the Advancement of Science, and 34 are members of the American Academy of Arts and Sciences, 5 to the American