Jesús Guillera, a Spanish mathematician, died on February 9, 2026, at the age of 70.
He specialized in number theory and was best known for his work on Ramanujan-type series for calculating the mathematical constant π. Largely self-taught in advanced mathematics, he later earned a doctorate from the University of Zaragoza and published extensively on hypergeometric identities, WZ-pairs, and related topics in analytic number theory.
Born in Zaragoza on December 31, 1955, Guillera spent much of his career teaching physics and mathematics at secondary schools in the province of Zaragoza before devoting himself more fully to mathematics.
Jesús Guillera (31 December 1955 – 9 February 2026) was a Spanish mathematician who specialised in number theory, best known for his work on Ramanujan-type series for calculating the mathematical constant π. Largely self-taught in advanced mathematics, he later earned a doctorate from the University of Zaragoza and since then published extensively on hypergeometric identities, WZ-pairs, and related topics in analytic number theory.