It is frequently emphasized that technology integration to the education of the students have intellectual disabilities has great importance. The researches performed show that using virtual manipulatives consist positive effects on learning mathematics on the students have intellectual disabilities. This study was done to investigate the addition operation learning process of the students have intellectual disabilities. Two students have mild intellectual disabilities and are 14 and 17 years old participated to this research conducted by means of multiple case study is one of the qualitative research designs. In this study was realized during five schedules data were collected through interviews, observations and documents. Content analysis were used for data analysis. At the end of the analysis, three categories of findings on "Learning of the addition operation", "Opinions on the use of computer and virtual manipulatives" and "Individual differences", were structured.