**Kurt Hensel** He was born on December 29, 1861 in Königsberg, Prussia (today Kaliningrad, Russia), and died on June 1, 1941 in Marburg, Germany. He invented the numbers *p-add*, an algebraic theory that has proved important in more recent applications.

Hensel studied mathematics in Berlin and Bonn. Among his teachers were Lipschitz, Weierstrass, Kirchhoff, Helmholtz and especially Kronecker. He spent several years editing Kronecker's collected works. His work followed that of Kronecker in the development of arithmetic in algebraic number fields.

In 1897 Weierstrass's method of developing series for algebraic functions led him to the invention of numbers. *p-add*. Hensel was interested in the exact cousin that divides the discriminant from an algebraic number field. The numbers *p-add* they can be considered as a conclusion of rational numbers, in a different way from the usual conclusion leading to real numbers.

Hensel's invention led to the development of the concept of a field with estimation that had a great influence on the most recent mathematics. He could use his methods to prove many results in quadratic form theory and number theory.

In 1923 that the potential of numbers *p-add* was demonstrated by Hasse when he formulated the local-global principle. He showed that an equation has a rational solution if and only if it has a solution in the numbers. *p-add* for each cousin p.

Hensel was a professor at the University of Marburg until his retirement in 1930. In 1901 he was the editor of the prestigious and influential Crelle Diary.