<![CDATA[The aim of this research is to develop and produce interactive multimedia- based LKPD on sequences and arithmeic series and improve the ability to understand mathematical concepts of class This type of research is R&D development research (research& development) using the 4D model (define, design, development, disseminate). The result of this research is an interactive multimedia-based worksheet on sequences and arithmetic series. Based on the validity test, it can be seen from the results of the LKPD assessment which was assessed by 2 lecturers and 1 mathematics teacher with an average percentage of 95% in the very valid category. Meanwhile,  the practicality test was carried out through teacher response questionnaires and student response questionnaires with an average assessment percentage of 96% in the very practical category, and to test effectiveness through a test of students' ability to understand mathematical concepts with an average student learning outcome of 81% in the category classically completed, and the observation results have an average assessment percentage of 95.7% in the very effective category. Thus it can be concluded that the student worksheets (LKPD) based on interactive multimedia on sequences and arithmetic series using the Discovery Learning model to improve the ability to understand mathematical concepts at X th Class students of SMA Negeri 6 Tanjungbalai are valid, practical and effective Keywords: Discovery learning, LKPD, interactive multimedia, ability to understand mathematical concepts]]>
