This study aims at determining the misconceptions and learning difficulties that students experience regarding general number and unknown which are different aspects of the use of the concept of variable. Two sub-problems were examined for this purpose. The first one is the comments of students on general number and the second one is their comments on unknown. A qualitative method (case study design) was used in this study. The data presented in this paper were obtained through the analysis of the students' answers to the tests designed in accordance with the examined issues, their work on the variable-related questions in the exam documents, and the interviews with some of them. The sample of this research consisted of 158 eight grade students. The results show that the subjects of this study experience a set of difficulties and have certain misconceptions in understanding the concept of variable. This paper presents these learning problems and considers means to improve the matters.