Real numbers are either irrational or rational.

The real numbers include all the rational numbers, such as the integer - 5 and the fraction 4/3, and all the irrational numbers, such as √2 (1.41421356 ..., the square root of 2, an irrational algebraicnumber). Included within the irrationals are the transcendentalnumbers, such as π (3.14159265 ...).