The Number System

Video Lesson: Rational and Irrational Numbers

In this video, Khan Academy teaches you what rational and irrational numbers are and how to tell them apart.

Video Lesson: Number Comparison

Khan Academy shows how to sort irrational numbers with radicals from least to greatest without using a calculator.

Rational or Irrational:

Practice identifying rational and irrational numbers.


Practice estimating the closest rational value to an irrational number.