Mathematics
Arabian mathematician Thabit ibn Qurra (a.k.a. Thebit) [b. Harran (Turkey), 836, d. Baghdad (Iraq), February 18, 901] translates Greek mathematical works, generalizes the Pythagorean theorem for all triangles, and tries to solve the problem of establishing Euclid's fifth, or parallel, postulate on the basis of the previous four postulates. See also 450 ce Mathematics; 1824 Mathematics.
Thabit proposes a formula that generates pairs of amicable numbers -- numbers for which the sum of divisors of one number are equal to the sum of the divisors of the other number and vice versa. The smallest such pair consists of 220 (divisors 1 + 2 + 4 + 5 + 10 + 11 + 20 + 22 + 44 + 55 + 110 = 284) and 284 (divisors 1 + 2 + 4 + 71 + 142 = 220). Thabit also discusses magic squares. See also 300 bce Mathematics; 1020 Mathematics.
PhysicsThabit develops a theory of static equilibrium covering beams, levers, and other bodies. See also 250 bce Tools.
