Most students practice abductive reasoning in solving mathematical problems that encourage creativity. This study analyses the process of making conjectures based on abductive reasoning. This study used a qualitative design and involved 106 undergraduate mathematics students enrolled in the mathematics course Introduction to Ring. We analyzed the students' conjectures on two mathematics problems. The study was completed by grouping the types of conjectures made by students and then investigating each student's explanation of each conjecture. The results suggested two types of conjectures practised by students, namely creativity in investigating the converse of the proposition and creativity in dividing into cases.