Misconceptions occur as a result of learners' wrong beliefs and experiences, and because subsequent learning is built on these misconceptions, they cause new concepts to be learned incorrectly. Studies show that students have problems in making sense of many mathematical concepts in mathematics teaching processes and this situation can be encountered at different learning levels. In this study, it was tried to determine the misconceptions of 9th grade students on the subject of numbers, since the studies were carried out at the primary or university level and the students' basic knowledge about different number sets was formed in the 9th grade. This research is in the scanning model. In this study, qualitative and quantitative data analysis methods were used together, and the interview method was used to collect qualitative data. Open-ended questions prepared by the researcher were used to collect the quantitative data of the study. The sample of the research consists of 50 9th grade students studying in Ankara in the 9th grade and participating in the study on a voluntary basis through easy sampling. As a result of the research, it is seen that 9th grade students generally have misconceptions about the definitions and representations of irrational and rational numbers, students who have misconceptions see all the numbers given in the root as irrational numbers and have difficulty in showing these numbers on the number line.