In 1801, in his Disquisitiones arithmeticae ("Arithmetical Reflections"), written entirely in Latin, the German mathematician Carl Friedrich Gauss explicitly introduced the notion of congruence: numbers were no longer to be studied in isolation, but together with all those that leave the same remainder when divided by a given number. Although this approach to arithmetic dates back to antiquity, Gauss's work would become a landmark in the history of number theory.
####
Carl Friederich Gauss (1777–1855).
Counting like a clock
-------------------------
