The
Disquisitiones Arithmeticae (
Latin:
Arithmetical Investigations) is a textbook of
number theory written in Latin by
Carl Friedrich Gauss in 1798 when Gauss was 21 and first published in 1801 when he was 24. In this book Gauss brings together results in number theory obtained by mathematicians such as
Fermat,
Euler,
Lagrange and
Legendre and adds important new results of his own.