Mostoles, R. 2026. Integrating Numeracy and Literacy Across the Curriculum: Challenges Encountered by Elementary Teachers of Osmeña Colleges in Promoting 21st-Century Skills, Personal Qualities, and Learner Competencies. International Journal of Sustainability and Advanced Integrated Research. 2, 2 (May 2026), 1849–1855. DOI:https://doi.org/10.65339/ijsair.V2.I2.392.