Review of postgraduate theses on decimal notation

The aim of this study is to examine the postgraduate theses prepared on decimal notation in accordance with the determined criteria (descriptive, methodological, etc.). For this purpose, as a result of a detailed search in the database of YOK National Thesis Centre, between the years 1999-2022, the words "decimal notation, decimal number and decimal fraction" were searched and accessible; The sample of the study consists of 32 master's and four doctoral theses, which were examined in line with 18 criteria. The criterion sampling method, which is one of the purposive sampling methods, was used in the selection of the sample. Document analysis, one of the qualitative analysis methods, was used for data analysis. The findings obtained as a result of this examination are presented in tables. According to the results of the study, the highest number of studies (f=8) were conducted in 2019, the number of studies conducted at Gazi University was the highest (f=5), and qualitative research methods were preferred most (f=14) as a research method. It has been seen that the sampling method was chosen among the purposive sampling methods in general, and the decimal fraction (f=13) was mostly used as the decimal discourse. It is important to increase studies that will contribute to the knowledge and experience of teachers and teacher candidates in order to overcome the difficulties experienced in the conceptual teaching and learning of decimal notation, which has differences in terms of the concept of digits. When the data collection tools are examined, it is seen that achievement test, observation and anxiety attitude scales are frequently preferred. Other data collection tools should also be actively used in studies, especially case studies and action researches. In addition to increasing the number of studies dealing with the difficulties of students in decimal notation, studies investigating which teaching methods and how solutions can be presented to these problems should also be included. In line with the data obtained from the study, it is thought that it will enable to see the deficiencies and weaknesses in the field of mathematics education, and will shed light on the studies to be carried out especially on the subject of decimal notation.