This math topic focuses on calculating the percentage values of given numbers, specifically in 5% increments up to 15%. It provides practice on understanding what specific percentages (10% and 15%, and one instance of 5%) represent when applied to various base values (100, 80, 60, 40, 20). The problems contain a mixture of multiple-choice questions aiming to strengthen fundamental percentage calculation skills. This topic is introductory and part of a broader unit on percentages.