<![CDATA[The aim of this study is to investigate the historical, philosophical, and mathematical aspects of Betawi traditional house architecture through an ethnomathematical perspective. A qualitative case study was conducted over a one-month period in 2025 at the officially designated Betawi Cultural Village of Setu Babakan, Jakarta, Indonesia. The bounded case comprised six replica houses which included two Bapang/Kebaya, two Gudang, and two Betawi Joglo/Limasan. A total of three Betawi cultural experts with each having more than 10 years of relevant experience participated in a semi-structured interview which lasted for 1.5-2.5 hours. Moreover, each house was observed twice for approximately four hours per session to produce 12 observations and approximately 48 hours of field observation. Interview transcripts, field notes, photographs, app-assisted measurement estimates, and analytical sketches were examined using hybrid thematic coding and hermeneutic interpretation supported by MAXQDA. The results identified culturally documented practices associated with measurement, proportional consideration, material selection, spatial arrangement, and construction design. Historical developments and philosophical meanings were interpretively related to the practices and observable architectural properties. Formal concepts such as geometric solids, symmetry, centroids, and coordinate representations were also used as researcher-generated analytical representations rather than attributed to the explicit terminology of the builders. This study contributes a hermeneutic account that distinguishes community-based mathematical practices, observable mathematical properties, and researcher-generated formal representations. The results can serve as a reference for future culturally responsive mathematics-learning materials. However, the educational effectiveness needs to be tested through a classroom-based study.]]>
