This article examined high school students’ basic mathematics skills. 126 Students participated in a study that lasted ten weeks in which a pretest and post-test were taken. In between the tests, students took weekly quizzes to refresh and relearn the following basic mathematics skills: adding, subtracting, multiplying, and dividing whole numbers, decimals, and fractions; proportions; conversion between percents, decimals, and fractions; and order of operations. The scores of the pretest and post-test were analyzed to see if improvements were made. Scores were compared by gender and grade level. The study showed an overall improvement on students’ ability to do basic math skills. Juniors and seniors in high school generally scored the lowest on individual quizzes. Improvement was analyzed according to the scores of the tests as well as students’ perspective on their own improvement. This study will help educators understand the knowledge their students have of basic skills. Consequently, educators will be able to incorporate basic skills into the daily classroom to help improve these skills in their students.