# Irrational Number

An irrational number is a number that cannot be expressed as a fraction, that is, it cannot be written as the quotient of two whole numbers. As a decimal, an irrational number is shown by an infinitely long nonrepeating sequence of numbers. Examples of irrational numbers are π (**pi**, the **ratio** of circumference to diameter of a **circle**), *e* (base of the natural **logarithms**), and √2 (that number which multiplied by itself equals 2).

See also e (number); Rational number.

## Additional topics

Science EncyclopediaScience & Philosophy: *Intuitionist logic* to *Kabbalah*