We will learn the addition of rational number with same denominator. In order to add two rational numbers having the same denominator, we follow the following steps:
Step I: Let us obtain the numerators of two given rational numbers and their common denominator.
Step II: Add the numerator of two given rational numbers obtained in step I.
Step III: Write a rational number whose numerator is the sum of two given rational numbers obtained in step II and retain the common denominator (simplify if required).
From the above follows steps we conclude that if \(\frac{a}{b}\) and \(\frac{c}{b}\) are two rational numbers with the same denominator, then \(\frac{a}{b}\) + \(\frac{c}{b}\) = \(\frac{a + c}{b}\).
1. Find the sum \(\frac{7}{9}\) + \(\frac{11}{9}\).
Solution:
\(\frac{7}{9}\) + \(\frac{11}{9}\)
= \(\frac{7 + (11)}{9}\)
= \(\frac{7  11}{9}\)
= \(\frac{4}{9}\)
2. Find the sum \(\frac{8}{11}\) + \(\frac{3}{11}\)
Solution:
We first express \(\frac{8}{11}\) as a rational number with positive denominator.
We have, \(\frac{8}{11}\) = \(\frac{8 × (1)}{(11) × (1)}\) = \(\frac{8}{11}\)
Therefore, (\(\frac{8}{11}\) + \(\frac{3}{11}\))
= (\(\frac{8}{11}\) + \(\frac{3}{11}\))
= \(\frac{(8) + 3}{11}\)
= \(\frac{5}{11}\)
2. Add \(\frac{7}{15}\) and \(\frac{9}{15}\).
Solution:
\(\frac{7}{15}\) + \(\frac{9}{15}\)
= \(\frac{(7) + (9)}{15}\)
= \(\frac{7  9}{15}\)
= \(\frac{16}{15}\), [Since, 7  9 = 16]
Therefore, \(\frac{7}{15}\) + \(\frac{9}{15}\) = \(\frac{16}{15}\).
3. Add \(\frac{6}{19}\) and \(\frac{8}{19}\).
Solution:
We first express \(\frac{6}{19}\) as a rational number with positive denominator.
We have, \(\frac{6}{19}\) = \(\frac{6 × (1)}{(19) × (1)}\) = \(\frac{6}{19}\)
Now, \(\frac{6}{19}\) + \(\frac{8}{19}\)
= \(\frac{6}{19}\) + \(\frac{8}{19}\)
= \(\frac{6 + 8}{19}\)
= \(\frac{2}{19}\), [Since, 6 + 8 = 2]
Therefore, \(\frac{6}{19}\) + \(\frac{8}{19}\) = \(\frac{2}{19}\).
● Rational Numbers
Introduction of Rational Numbers
Is Every Rational Number a Natural Number?
Is Every Rational Number an Integer?
Is Every Rational Number a Fraction?
Equivalent form of Rational Numbers
Rational Number in Different Forms
Properties of Rational Numbers
Lowest form of a Rational Number
Standard form of a Rational Number
Equality of Rational Numbers using Standard Form
Equality of Rational Numbers with Common Denominator
Equality of Rational Numbers using Cross Multiplication
Comparison of Rational Numbers
Rational Numbers in Ascending Order
Rational Numbers in Descending Order
Representation of Rational Numbers on the Number Line
Rational Numbers on the Number Line
Addition of Rational Number with Same Denominator
Addition of Rational Number with Different Denominator
Properties of Addition of Rational Numbers
Subtraction of Rational Number with Same Denominator
Subtraction of Rational Number with Different Denominator
Subtraction of Rational Numbers
Properties of Subtraction of Rational Numbers
Rational Expressions Involving Addition and Subtraction
Simplify Rational Expressions Involving the Sum or Difference
Multiplication of Rational Numbers
Properties of Multiplication of Rational Numbers
Rational Expressions Involving Addition, Subtraction and Multiplication
Reciprocal of a Rational Number
Rational Expressions Involving Division
Properties of Division of Rational Numbers
Rational Numbers between Two Rational Numbers
8th Grade Math Practice
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● Rational Numbers  Worksheets
Worksheet on Equivalent Rational Numbers
Worksheet on Lowest form of a Rational Number
Worksheet on Standard form of a Rational Number
Worksheet on Equality of Rational Numbers
Worksheet on Comparison of Rational Numbers
Worksheet on Representation of Rational Number on a Number Line
Worksheet on Adding Rational Numbers
Worksheet on Properties of Addition of Rational Numbers
Worksheet on Subtracting Rational Numbers
Worksheet on Addition and
Subtraction of Rational Number
Worksheet on Rational Expressions Involving Sum and Difference
Worksheet on Multiplication of Rational Number
Worksheet on Properties of Multiplication of Rational Numbers
Worksheet on Division of Rational Numbers
Worksheet on Properties of Division of Rational Numbers
Worksheet on Finding Rational Numbers between Two Rational Numbers
Worksheet on Word Problems on Rational Numbers