Learning in the 21st century requires the ability of students who are critically oriented, communicative, and innovative, as well as implementnumeration skills. Problem-Based Learningmodel combined with Lesson Study becomes one of the implementation ways to improve numeration skill. The facts show that numerical literacy skills remain low in Indonesia. Students in class IX F SMP Muhammadiyah 08 Batu frequently struggle with analyzing science material questions presented in the form of calculations and diagrams. This research aimed at discovering the students numeration skill based on their learning outcomes, particularly on the material of sexually transmitted diseases (STD). The research method used was exploratory descriptive, and the study was conducted at SMP Muhammadiyah 08, Batu City, Malang, during the odd semester period (2022/2023). 25 students of IX-F class were used as the object of this research, of which students were grouped into six groups. This research was based on the Lesson Study for Learning (LS-LC) stages of the plan, do, and see. Student Worksheets (LKPD) and teacher assessment rubrics served as the researchinstruments. The obtained data were analyzed descriptively, quantitatively, and qualitatively. This research indicates that by using the LS-based PBL model, there is an increase in the average student results in cycle one between the first and second meetings, namely 83.3 to 88.9. In cycle II, the first and second meetings present a significant increase in student learning outcomes, ranging from 82.6 to 95.8. Based on these findings, it is possible to conclude that the PBL learning model improves the students numerical literacy skills at SMP Muhammadiyah 08 Batu.