Melissa Fastuca chairs the Mathematics Department.

Depending on what year students entered the ninth grade, they are required to take either three credits or four years of mathematics. Algebra I is a prerequisite for both geometry and Algebra II. At Perry Hall High School, students usually take geometry before Algebra II. A variety of courses are available after Algebra II; which course(s) students take after those three courses is a function of what year of high school the student is entering and the student's performance in those courses.

Depending on "cohort" (the calendar year that a student enters high school), students may be required to pass the Maryland High School Assessment in Algebra/Data Analysis or one or more PARCC tests. PARCC tests have been written for Algebra I and for geometry.

Perry Hall High School offers courses that prepare students for College Board's Advanced Placement tests for AP Calculus (both AB and BC) and AP Statistics.