After three decades of research and the help of a supercomputer, mathematicians have discovered a new Dedekind number, D(9), a 42-digit integer. Dedekind numbers are complex mathematical concepts related to Boolean functions. The calculation of D(9) was a long-standing challenge in the field, solved using the Noctua 2 supercomputer at the University of Paderborn, Germany. The discovery marks a significant milestone in the study of these special integers.