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First to treat zero as a number and define rules for negatives.

Gave the world algebra and, through his own name, the algorithm.

Founded optics and the experimental method in the Book of Optics.

Measured Earth's radius to within 1% and wrote the first comparative anthropology of India.

Solved cubics geometrically, reformed the calendar, wrote the Rubaiyat.

Tusi couple; his planetary models likely reached Copernicus.

Sultan-astronomer whose star catalogue stood unmatched for two centuries.