Nafis, Ari Mahardika Ahmad, and Darlis Herumurti. 2020. “EFFECTIVENESS STUDIES OF THE LEARNING BASIC MATHEMATICAL OPERATIONS ON USERS USING EDUCATION GAMES WITH ESCALATING DIFFICULTY LEVEL IN SEVERAL TYPES OF GAMES”. JUTI: Jurnal Ilmiah Teknologi Informasi 18 (2): 115-24. https://doi.org/10.12962/j24068535.v18i2.a989.