Pemahaman Nilai Phi (Π) terhadap Rumus Keliling Lingkaran pada Mahasiswa PGSD 2018 Unirow Tuban

As a prospective educator, especially Unirow Tuban students are expected to have adequate competition. The competence in question is primarily the mastery of mathematics learning material that will be taught to elementary school students. One of the material that is often considered easy but in fact many educators and even students also have difficulty in teaching is to understand the value of phi (π) in the formula around the circle. An interview with one of the 2018 students revealed that the student did not know the origin of the phi (π) value in the circle circumference formula, which students remembered when learning circle material sometimes began by giving a formula around the circle, then continued by completing the example problems. This study aims to analyze and describe students' understanding of the phi (π) numbers in the formula around the circle. This type of research is descriptive with a qualitative approach. The research subjects were 70 students. The data collection technique used a random sampling of 75 students. In order to measure the ability of students to do the test. Based on the results of data analysis, it can be concluded that the 2018 PGSD Unirow Tuban students have an understanding that is still very low with an average score of 58.7 in the poor category with a conversion of D scores. Most students have difficulty understanding, especially in point C questions. and point D related to the origin of the phi (π) value and how to find the phi (π) value itself. If it is tested on question C, students are able to answer the meaning of the phi (π) value as much as 18.66% (14) students. While in question D, students are able to answer how to find the value of phi (π) by 16% (12) students