The purpose of this study is to examine teachers, in the elementary grades 2 and 3, view on pupils ' understanding of regrouping in subtraction algorithms and the use of concrete materials to facilitate pupils' understanding of regrouping in subtraction algorithms. The study emanates from teachers who teach, or have taught, in regrouping in subtraction algorithms in the elementary grades of 2 and 3. With the use of a semi-structured interview, we were able to gain an understanding of teachers' opinions and experience about pupils' understanding of regrouping in subtraction algorithms and their use of concrete materials to facilitate pupils' understanding.  The teachers in our study agree on the fact that pupils can have difficulties with regrouping in subtraction algorithms. The study shows that the teachers´ opinions and experience indicate that concrete materials can facilitate pupils' understanding of mathematics, but they also show different opinions and experiences for whom the opportunities exist. Furthermore, the results of the study show that the teachers who participated in the study can also see limitations in using concrete materials in their mathematics teaching, such as the amount of material that is available, that the concrete material invites to play and more. Most of the teachers teach with concrete material for regrouping in subtraction algorithms to facilitate the pupils understanding and to provide clarity for the pupils, as seen from the results of the study. Furthermore, the results show that there are teachers who do not teach with concrete materials for regrouping in subtraction algorithms.