section_path: Formal definitions/Construction from the rational numbers
section_name: Construction from the rational numbers
paragraph_text: Construction from the rational numbers
  
  The real numbers can be constructed as a completion of the rational numbers, in such a way that a sequence defined by a decimal or binary expansion like (3; 3.1; 3.14; 3.141; 3.1415;...) converges to a unique real number—in this case π. For details and other constructions of real numbers, see Construction of the real numbers.