He also studied (1909–1910) at Columbia, where he was a fellow and a university extension lecturer. He taught at Berea College and at Oswego, New York at the Normal School there, then accepted a position at Michigan where in 1919 he became full professor of mathematics. Dr. Karpinski devoted his attention chiefly to the history and pedagogy of mathematics.
An authority on the history of science, he was collaborator on the Archivo di Storia della Scienza and author of The Hindu-Arabic Numerals, with David Eugene Smith (1911), Robert of Chester's Latin Translation of the Algebra of Al-Khowarizmi (1915), and Unified Mathematics, with H. Y. Benedict and J. W. Calhoun (1913), and subsequently produced other publications. He served as the president of the History of Science Society from 1943-44.