section_path: Main classification
section_name: Main classification
paragraph_text: Main classification
  
  Numbers can be classified into sets, called number sets or number systems, such as the natural numbers and the real numbers. The main number systems are as follows:
  
  Each of these number systems is a subset of the next one. So, for example, a rational number is also a real number, and every real number is also a complex number. This can be expressed symbolically as
  
  A more complete list of number sets appears in the following diagram.