What is a rational or irrational number?

1 Answer
Mar 28, 2016

A rational number is one that can be written as an integer over an integer, with non-zero denominator. ie. all your fractions.

The set of rational numbers is hence given in set notation as

#QQ={m/n;m,n in ZZ; n!=0}#

An irrational number cannot be expressed as a ratio of integers and include numbers such as #pi, e, sqrt2, ln2#, etc.
The set of irrational numbers #=RR-QQ#.