-1 is rational. Math textbook for the second semester of the second grade (Beijing Normal University Edition) Chapter II How can the number of the first lesson of real numbers be less than 35 pages? In fact, rational numbers can always be expressed by finite decimals or infinite circulating decimals. Conversely, any finite decimal or infinite cyclic decimal is also a rational number.

-1 is a negative number in a finite decimal and is a part of an integer.