K.A. Semendyaev. Life and scientific achievements

The preprint is devoted to the life and scientific work of the outstanding Soviet scientist in the field of applied mathematics Konstantin Semendyaev (1908–1988). As a recognized authority on carrying out massive computational work on the basis of manual counting, he was involved in the numerical calculations of the tasks of creating atomic weapons. Based on documentary materials, the significant contribution of K.A. Semendyaev to the creation of methods for numerical solution and the necessary calculations in the Atomic Project is shown.