Addition of Unlike Fractions

We will learn how to solve addition of unlike fractions.

In order to add unlike fractions, first we convert them as like fractions with same denominator in each fraction with the help of method explained earlier and then we add the fractions.

Let us consider some of the examples of adding unlike fractions:

1. Add 7/8 and 9/10

Solution:

The L.C.M. of the denominators 8 and 10 is 40.

7/8 = (7 × 5)/(8 × 5) = 35/40 , (because 40 ÷ 8 = 5)

9/10 = (9 × 4)/(10 × 4) = 36/40, (because 40 ÷ 10 = 4)

Thus, 7/8 + 9/10

= 35/40 + 36/40

= (35 + 36)/40

= 71/40

= 1 31/40


2. Add 1/6 and 5/12

Solution:

Let L.C.M. of the denominators 6 and 12 is 12.

1/6 = (1 × 2)/(6 × 2) = 2/12, (because 12 ÷ 6 = 2)

5/12 = (5 × 1)/(12 × 1) = 5/12, (because 12 ÷ 12 = 1)

Thus, 1/6 + 5/12

= 2/12 + 5/12

= (2 + 5)/12

= 7/12


3. Add 2/3, 1/15 and 5/6

Solution:

The L.C.M. of the denominators 3, 15 and 6 is 30.

2/3 = (2 × 10)/(3 × 10) = 20/30, (because 30 ÷ 3 = 10)

1/15 = (1 × 2)/(15 × 2) = 2/30, (because 30 ÷ 15 = 2)

5/6  = (5 × 5)/(6 × 5) = 22/30, (because 30 ÷ 6 = 5)

Thus, 2/3 + 1/15 + 5/6

= 20/30 + 2/30 + 25/30

= (20 + 2 + 25)/30

= 47/30

= 1 17/30

Related Concept

Fraction of a Whole Numbers

Representation of a Fraction

Equivalent Fractions

Properties of Equivalent Fractions

Like and Unlike Fractions

Comparison of Like Fractions

Comparison of Fractions having the same Numerator

Types of Fractions

Changing Fractions

Conversion of Fractions into Fractions having Same Denominator

Conversion of a Fraction into its Smallest and Simplest Form

Addition of Fractions having the Same Denominator

Subtraction of Fractions having the Same Denominator

Addition and Subtraction of Fractions on the Fraction Number Line



4th Grade Math Activities

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