Studies reveal that students as well as teachers have difficulties in understanding and learning of decimals. The purpose of this study is to investigate students' as well as pre-service teachers' solution strategies when solving a question that involves an estimation task for the value of a decimal number on the number line. We also examined the pre-service teachers' anticipation of students' misconceptions and difficulties for the given task. To conduct our analysis, we conducted interviews with three 5th and three 6th grade students, and eight preservice teachers. During the interviews we asked them to solve the question and explain their solution strategies. The findings of the study indicate that students and pre-service approach this problem in different ways. However, both groups have a tendency to think of decimals successively and indicate precise answers rather than specifying a range of possible values. We also observed the preservice teachers could only partially anticipate the misconceptions and difficulties faced by the students.