Class 7 Operations on Rational Numbers — practice questions with answers

Rational Numbers · 5 sample questions from the school syllabus. Try each one, then open the answer and the worked solution.

1. Add:

\frac{2}{7} + \frac{3}{7}

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Answer: A)

\frac{5}{7}

Same denominator, so add numerators:

\frac{2 + 3}{7} = \frac{5}{7}

2. Which rational number is the additive inverse of

\frac{5}{11}

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Answer: A)

- \frac{5}{11}

Additive inverse changes only the sign:

- \frac{5}{11}

3. Evaluate:

\frac{1}{2} + \frac{1}{3} - \frac{1}{6}

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Answer: A)

\frac{2}{3}

LCM 6:

\frac{3}{6} + \frac{2}{6} - \frac{1}{6} = \frac{4}{6} = \frac{2}{3}

4. Sita reads

\frac{1}{3}

of a story book on Monday and

\frac{2}{5}

of the same book on Tuesday.
What fraction of the book has she read in total?

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Answer: A)

\frac{11}{15}

LCM 15:

\frac{5}{15} + \frac{6}{15} = \frac{11}{15}

5. Rohit thinks of a rational number. He adds

\frac{1}{2}

, then multiplies the result by

\frac{2}{3}

, and gets 1.
What number did Rohit think of?

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Answer: A) 1

Let the number be n.

(n + \frac{1}{2}) \times \frac{2}{3} = 1

, so

n + \frac{1}{2} = \frac{3}{2}

, giving

n = \frac{3}{2} - \frac{1}{2} = 1

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