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Approximate Irrational Numbers


Videos and lessons to help Grade 8 students learn how to use rational approximations of irrational numbers to compare the size of irrational numbers, locate them approximately on a number line diagram, and estimate the value of expressions (e.g., π2). 

For example, by truncating the decimal expansion of √2, show that √2 is between 1 and 2, then between 1.4 and 1.5, and explain how to continue on to get better approximations

Common Core: 8.NS.2

Suggested Learning Targets

  • I can approximate irrational numbers as rational numbers
  • I can approximately locate irrational numbers on a number line
  • I can estimate the value of expression involving irrational numbers using rational.
    (Examples: Being able to determine the value of the √2 on a number line lies between 1 and 2, more accurately, between 1.4 and 1.5, and more accurately, etc.)
  • I can compare the size of irrational numbers using rational approximations.

Related Topics:
Common Core for Grade 8

Common Core for Mathematics

More Math Lessons for Grade 8

8NS2 Approximating the Values of Irrational Numbers
Know that there are numbers that are not rational, and approximate them by rational numbers.

8NS2 Estimating the Value of Irrational Expressions part 1.

8NS2 Estimating the Value of Irrational Expressions part 2.

Estimating the Value of Irrational Numbers.


8.NS.2 Rational Approximations of Irrational Numbers
Approximate square root of numbers that are not prefect squares and put them on the number line.

Compare irrational and rational numbers - 8.NS.1
In this lesson, you will learn to compare an irrational number to a rational number or to another irrational number.

Estimating Irrational Numbers
An instructional math video on how to make estimations about the value of irrational square roots.

Estimating Square Roots.


Rotate to landscape screen format on a mobile phone or small tablet to use the Mathway widget, a free math problem solver that answers your questions with step-by-step explanations.

You can use the free Mathway calculator and problem solver below to practice Algebra or other math topics. Try the given examples, or type in your own problem and check your answer with the step-by-step explanations.

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