DEWI MULIYANA, NIM. 2110247636, Development of Contextual Problem-Based Teaching Materials Material on Sequences and Series to Improve the Mathematical Problem Solving Ability of Class X Students, supervised by Atma Murni and Sehatta Saragih. This research is motivated by the importance of mathematical problem solving abilities (KPMM) in the 21st century. However, this is inversely proportiona…