Decimal Expansions of Rational Numbers

8th Grade60 minutesKY.8.NS.1 Understand informally that every number has a decimal expansion; the rational numbers are those with decimal expansions that terminate in 0s or eventually repeat. Know that other numbers are called irrational.

Learning Objective

I can explain how rational numbers have decimal expansions that terminate or repeat.

Key Concepts

Rational numbers can be expressed as either terminating decimals or non-terminating recurring decimals.

To determine if a fraction will result in a terminating or non-terminating decimal, reduce the denominator to its prime factors.

If the prime factors of the denominator are only 2 or 5, the decimal will terminate; otherwise, it will be a non-terminating recurring decimal.

Practice Questions

This lesson includes 12 practice questions to reinforce learning.

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1. What are the two possible types of decimal expansions for rational numbers?

2. Express the number 7/8 as a decimal. Is it terminating or non-terminating recurring?

3. Without performing division, how can you determine whether the fraction 3/16 will result in a terminating or non-terminating recurring decimal?

...and 9 more questions

Educational Video

Trick to Identify Terminating Rational Numbers & Non-Terminating Recurring Decimals | Don't Memorise

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