Thabit ibn Qurra
Sabian mathematician, physician, and translator who made fundamental contributions to number theory and geometry.
Who or what
Abu'l-Hasan Thabit ibn Qurra ibn Marwan al-Sabi al-Harrani (826–901) was a Sabian mathematician, physician, astronomer, and translator from Harran.
He worked at the House of Wisdom and made pioneering contributions to number theory, geometry, and mechanics.
Why it mattered
Thabit discovered the formula for amicable numbers — pairs of numbers where each equals the sum of the other's proper divisors.
He also generalized the Pythagorean theorem and made important advances in integral calculus.
Key works and moments
His amicable pair (220, 284) was known to the Greeks, but Thabit's general formula allowed generation of many more.
He generalized the Pythagorean theorem to arbitrary triangles in his "Book on the Measurement of Parabolic Solids."
Further detail
Thabit's rule: if , , and are all prime, then and form an amicable pair.
He used the method of exhaustion (attributed to Archimedes) to compute volumes of paraboloids.
Legacy
His work on amicable numbers laid foundations for number theory developed later by Euler and Fermat.
His translations of Archimedes, Euclid, and Ptolemy preserved these works and made them available to later Islamic and European scholars.
More in Islamic Golden Age
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