Real Numbers
The set formed by the rational numbers and irrational numbers is the set of real numbers, and is designated by 
.
With real numbers all operations can be performed, except for the root of an even index and negative radicand, and division by zero.
The Real Line
For any real number there is a point on the straight line and for every point on the straight line, a real number.
Representation of Real Numbers
The real numbers can be represented in the straight line with as much approximation as needed, but there are cases in which they can be represented in exact form.
