The number of test-takers choosing Probability and Statistics over Calculus or Geometry as their math elective on Korea's College Scholastic Ability Test (CSAT) for the 2027 academic year is expected to far exceed those selecting Calculus or Geometry. The so-called "Prob & Stats rush" reflects a strategy of choosing Probability and Statistics — which requires two to three times less study than Calculus — to free up time for Korean language and other exam subjects. However, as this trend is expected to increase the number of incoming science and engineering students who must be taught calculus from scratch at university, concerns over declining talent competitiveness are substantial.
According to Megastudy Education on Tuesday, 49.5% of all math test-takers chose Probability and Statistics in this year's first nationwide mock exam held last month. That marks a 19.5 percentage point surge compared to the March mock exam last year. Meanwhile, the share of students choosing Calculus dropped from 68.0% to 48.3% over the same period — a decline of 19.7 percentage points.
The Prob & Stats rush trend is also evident in actual CSAT figures. In the 2025 academic year CSAT, 173,215 students chose Probability and Statistics, fewer than the 196,198 who chose Calculus. But in the 2026 academic year CSAT, 264,355 students chose Probability and Statistics, surpassing the 193,395 who selected Calculus.
This shift emerged because, starting from the 2025 academic year, students choosing Probability and Statistics became eligible to apply to most top-tier natural science programs except Seoul National University. Science-track students began flocking to Probability and Statistics to reduce their study burden. Seoul National University still requires Calculus or Geometry for all natural science departments except Food and Nutrition, Textiles and Fashion, and Nursing.
Other universities designated Calculus or Geometry as mandatory on a department-by-department basis. According to a survey by Jongno Academy, seven out of 174 universities nationwide designated Calculus or Geometry as mandatory for some natural science departments. Gachon University designated its Cloud Engineering department; Kyungpook National University its Mobile Engineering department; Jeonbuk National University its Mathematics Education department; Jeju National University its Mathematics Education department; Chungnam National University three departments including Mathematics, Mathematics Education, and Information Statistics; Chungbuk National University three departments including Mathematics, Mathematics Education, and Information Statistics; and Chonnam National University 21 departments including Mechanical Engineering.
Additionally, aside from some departments at Hongik University and Dongguk University, no natural science programs offer bonus points for choosing Calculus or Geometry. In effect, choosing Probability and Statistics carries almost no disadvantage in university admissions.
Furthermore, analysts say the narrowing gap in maximum standardized scores between math electives since the 2025 academic year CSAT has also fueled the Prob & Stats rush. Generally, when a test is more difficult and average scores drop, maximum standardized scores rise; conversely, when a test is easier, maximum standardized scores fall. The gap in maximum standardized scores between Calculus and Probability and Statistics on the CSAT math section reached 11 points for the 2024 academic year but narrowed to 5 points for 2025 and 2 points for 2026.
In the 2024 academic year CSAT math section, based on the first-grade cutoff standardized score of 133, students who chose Probability and Statistics had a raw score of 94, while those who chose Calculus scored only 81. In the 2026 academic year CSAT, based on the first-grade cutoff standardized score of 128, Probability and Statistics students scored 88 in raw points while Calculus students scored 85 — a gap of just 3 points. Two years ago, students with the same raw score in Probability and Statistics and Calculus saw a roughly 13-point difference in standardized scores. But last year, a Probability and Statistics student needed to answer only one more question correctly than a Calculus student to receive a similar standardized score.
The Prob & Stats rush is readily observable in the private tutoring sector as well. "The number of students choosing Probability and Statistics has clearly been rising since last year, and this year more than half of students are selecting it," said Kim Won-jung, director of admissions strategy at Daesung Academy. "This phenomenon is driven by the fact that Calculus requires roughly three times the study volume compared to Probability and Statistics," Kim added.
However, top-tier students are still expected to stick with Calculus. Even as the standardized score gap between electives narrows, Calculus still yields higher standardized scores, and most essay-based admissions exams for natural science programs include Calculus. For medical schools, 17 universities including Seoul National University and the University of Ulsan require Calculus or Geometry, and Soonchunhyang University and Kangwon National University offer a 10% bonus for selecting those subjects.
Some analysts caution that the Prob & Stats rush may not be unconditionally advantageous on this year's CSAT. The Korea Institute for Curriculum and Evaluation has stated it will set the exam at an appropriate difficulty level within the public education curriculum, but adjustments to difficulty by elective subject are likely as the institute seeks to maintain score differentiation. If the institute adjusts difficulty in response to the tilt toward Probability and Statistics, the maximum standardized score gap between electives could widen again.
Given that major universities are already teaching high school-level calculus to incoming natural science freshmen due to declining academic readiness, critics point out that the Prob & Stats rush is negatively affecting higher education overall. This decline in academic readiness is expected to steepen further from the 2028 academic year, when the distinction between natural science and humanities tracks in CSAT math will be effectively abolished for the first time in 33 years. As a result, Calculus and Geometry will essentially disappear from the CSAT math exam scope.
"The math proficiency of students entering science and engineering programs could change significantly from what it used to be, and since the 2026 academic year, students have already been gravitating toward 'liberal arts math,'" said Lim Sung-ho, CEO of Jongno Academy. "Various policy reviews may be needed, including whether this CSAT reform is consistent with the government's 'policy to intensively foster science and engineering' and how universities should respond," Lim added.