This research aims to assess the basic arithmetic computational skills of students at Don Manuel Rivera Memorial Integrated National High School, emphasizing the importance of addressing foundational skill gaps early in students’ academic careers. The study identifies a critical problem: a significant percentage of students perform at "Low" and "Very Low" levels in arithmetic, potentially hindering their success in more advanced mathematical subjects. Using a comprehensive assessment methodology, data were gathered from 2,150 students across Grades 7-11, with statistical analyses employed to evaluate performance levels. The results reveal that 1.72% of students are classified as "Very Low," and 3.44% (74 students) as "Low," accounting for 5.16% of the student body, with Grade 7 showing 15 students (0.70%) in the "Very Low" category, indicating a crucial intervention point. These findings highlight the immediate need for structured remedial interventions, such as targeted tutoring and individualized instruction, to improve students’ arithmetic skills. The implications of this research extend to instructional practices reinforcing the need for continuous monitoring and early identification of struggling students. Recommendations include implementing targeted remedial programs, establishing peer tutoring initiatives, conducting regular assessments, and enhancing parental involvement in skill-building activities at home. By addressing these gaps, the school can create a more supportive learning environment, equipping all students with essential numeracy skills for future academic challenges.