This study aims to determine pre-service teachers' perceptions from different disciplines about number sense and reveal the strategies used to serve the components of number sense. The study is designed qualitatively, according to the phenomenology design. The study group consisted of a total of 265 pre-service teachers, 92 from Preschool Education Department (PSED), 88 from Classroom Instruction Education Department (CIED), and 85 from Primary Mathematics Education Department (PME). Three different (F1, F2 and F3) data collection tools were employed in the study. F1 was distributed to 265 pre-service teachers. After analyzing the data collected with F1, interviews were conducted with nine pre-service teachers (3 from each discipline) who employed different solutions using F2. The focus group was conducted with 12 pre-service teachers (4 from each discipline) selected from 24 volunteer pre-service teachers from different disciplines who use different strategies. The data of this session was collected through F3. Descriptive and content analysis were used in the data analysis. According to the findings, pre-service teachers' perceptions about number sense are grouped under four categories: ability, comprehension, number-processing knowledge, and intrinsic situations. The strategies developed depending on pre-service teachers' perception of number sense differed according to discipline.