MathematicsClass 8Rational Numbers

Rational Numbers Between Two Rational Numbers

Finding infinite rational numbers lying between any two given distinct rational numbers.

Class 8 · MathematicsCBSE & ICSE SOF IMO IOQM

Definition

There are infinitely many rational numbers between any two distinct rational numbers. To find them, we can make the denominators of the two rational numbers equal using the LCM method or use the mean method by averaging the two numbers.

Key formula

Mean method: (a + b) / 2

Worked examples

1

To find rational numbers between 1/3 and 1/2, make denominators equal to 6 (2/6 and 3/6), then multiply numerator and denominator by a larger factor like 10 to get 20/60 and 30/60, revealing numbers like 21/60, 22/60, etc.

2

Using the mean method between 1 and 2: (1 + 2) / 2 = 3/2.

3

Finding rational numbers between -1/4 and 1/4 results in 0, 1/8, -1/8, etc., after adjusting denominators.

Common mistakes

  • Believing there are only a finite number of rational numbers between two given fractions.
  • Adding fractions directly without making their denominators equal first when using the equivalent fraction method.
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