In this study, it was aimed to teach the addition and subtraction to a student with dyscalculia who is in third grade at elementary school. Before preparing individualized program, the student was given a pretest to measure about his level of the subject. The instruction was carried out in a room in the school, with a time of 40 minutes per day in the form of individual instruction with the student. In addition, the study was supported by a researcher-developed scenario booklet, concrete materials, computer games, reinforcement award, and assignments. This study was conducted as a case study, one of the qualitative research methods. The data were analyzed by descriptive analysis technique. Results of the study indicate that the student achieved more than 90 % objectives on teaching basic addition and subtraction skills at the third grade. Gains have been actualized by the student with mathematic learning difficulties with over 90 % success in 63 individualized lessons. On the other hand, social validity data were collected through observation and interviews to identify strengths or weaknesses and changes occurring in the student work. As a result of the studies, it has been determined that the student gained self-confidence by enjoying his sense of accomplishment.