Cubes and Cube Roots — Class 8 MCQs with Answers
Class 8 CBSE Mathematics · Chapter 106
Pre-2026 syllabusThis chapter is from the older NCERT book. See the 2026-27 Class 8 Mathematics chapters →
72 practice questions · 24 Easy · 24 Medium · 24 Hard · Updated
Practise the most important Class 8 CBSE Mathematics questions from Chapter 106, "Cubes and Cube Roots". You get 9 timed quizzes made from 72 NCERT-based MCQs, with answers and explanations. The questions are split into 24 Easy, 24 Medium and 24 Hard. Warm up on the basics, then move on to the exam-level questions that set top scorers in CBSE Board exams apart.
To score well in "Cubes and Cube Roots", focus on fast problem-solving, formula recall and step-by-step working. Each MCQ here is timed and uses exam-style marking (+4 correct, −1 wrong, 0 skipped). This trains you to stay accurate under time pressure, as real papers need. Every question has a short explanation, so a wrong answer becomes a quick lesson. It is the fastest way to fix gaps before a test.
Use this chapter for focused revision. Start with the Easy set to check your basics on Cubes and Cube Roots, then move to Medium and Hard to practise applying them. Your accuracy, streaks and XP save automatically. This chapter also adds to your overall Class 8 Mathematics mastery score. 14 sample questions are solved in full below, with the answer and a worked explanation. Sign in free to start practising.
Key concepts: Cubes and Cube Roots (Class 8 Mathematics)
This chapter covers perfect cubes, their properties, and finding cube roots by prime factorisation.
- Cube of a number
- The result of multiplying a number by itself three times, e.g. 2³ = 8.
- Perfect cube
- A number that is the cube of an integer (1, 8, 27, 64, …).
- Making a perfect cube
- Multiply or divide by the smallest number so that every prime factor appears in groups of three.
- Cube root
- The number whose cube gives the original number; written ∛x.
Cubes and Cube Roots — important questions & MCQs with answers (Class 8 Mathematics)
14 solved questions from this chapter's difficulty levels, each with its answer and explanation. The other 58 are timed and scored when you sign in.
- Q1Easy
Cube of 4:
A.12B.64✓ CorrectC.16D.32Answer: B. 64
Explanation: 4³ = 64.
- Q2Easy
∛125 =
A.5✓ CorrectB.25C.15D.125Answer: A. 5
Explanation: 5³ = 125.
- Q3Easy
What is the cube of 7?
A.294B.49C.21D.343✓ CorrectAnswer: D. 343
Explanation: 7³ = 7 × 7 × 7 = 343.
- Q4Easy
∛27 =
A.3✓ CorrectB.6C.9D.27Answer: A. 3
Explanation: 3³ = 27, so ∛27 = 3.
- Q5Easy
The value of 10³ is:
A.100B.30C.1000✓ CorrectD.10000Answer: C. 1000
Explanation: 10³ = 10 × 10 × 10 = 1000.
- Q6Easy
∛64 =
A.2B.8C.16D.4✓ CorrectAnswer: D. 4
Explanation: 4³ = 64, so ∛64 = 4.
- Q7Medium
Cubes of negative numbers are:
A.ZeroB.PositiveC.Negative✓ CorrectD.RandomAnswer: C. Negative
Explanation: (−2)³ = −8.
- Q8Medium
∛216 by prime factorisation:
A.4B.8C.12D.6✓ CorrectAnswer: D. 6
Explanation: 216 = 2³·3³ ⇒ ∛216 = 6.
- Q9Medium
By what smallest number must 72 be multiplied to make it a perfect cube?
A.2B.3✓ CorrectC.9D.6Answer: B. 3
Explanation: 72 = 2³·3²; multiplying by 3 gives 2³·3³ = 216, a perfect cube.
- Q10Medium
Using prime factorisation, ∛512 =
A.8✓ CorrectB.6C.7D.9Answer: A. 8
Explanation: 512 = 2⁹ = (2³)³, so ∛512 = 2³ = 8.
- Q11Medium
By what smallest number must 135 be divided to make it a perfect cube?
A.9B.3C.5✓ CorrectD.15Answer: C. 5
Explanation: 135 = 3³·5; dividing by 5 leaves 3³ = 27, a perfect cube.
- Q12Hard
Smallest number to multiply 392 to make it a perfect cube:
A.49B.3C.7✓ CorrectD.14Answer: C. 7
Explanation: 392 = 2³·7². Multiply by 7 to get 2³·7³.
- Q13Hard
∛729 =
A.9✓ CorrectB.7C.11D.3Answer: A. 9
Explanation: 9³ = 729.
- Q14Hard
1729 is the Hardy–Ramanujan number, the smallest number expressible as a sum of two cubes in two ways. One way is 1³ + 12³. What is the other?
A.9³ + 10³✓ CorrectB.2³ + 11³C.4³ + 11³D.6³ + 11³Answer: A. 9³ + 10³
Explanation: 9³ + 10³ = 729 + 1000 = 1729, matching 1³ + 12³ = 1 + 1728 = 1729.
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Start this chapter free →Cubes and Cube Roots — FAQs
What are the key concepts in Class 8 Mathematics Cubes and Cube Roots?+
This chapter covers perfect cubes, their properties, and finding cube roots by prime factorisation. Key ideas include Cube of a number, Perfect cube, Making a perfect cube, Cube root.
What does Class 8 Mathematics Chapter 106 (Cubes and Cube Roots) cover on XamBaaz?+
It has 72 NCERT-based MCQs on "Cubes and Cube Roots": 24 Easy, 24 Medium and 24 Hard. Together they make 9 timed quizzes, and you never get the same set twice. Every question has an instant explanation. They help you prepare for CBSE Board exams.
Are these "Cubes and Cube Roots" questions free to practise?+
Yes. Sign in with Google to practise "Cubes and Cube Roots" free. Full unlimited access is ₹999/year on a launch offer until 1 December 2026. No chapter is charged separately.
How should I revise "Cubes and Cube Roots" for the exam?+
Start with the Easy quiz to check your basics, then try Medium and Hard to practise applying them. There are 9 timed quizzes on this chapter, so you can come back for a fresh set instead of one you have seen. Read each explanation, retry the questions you miss, and track your accuracy until it stays high.
Are these "Cubes and Cube Roots" MCQs available with answers?+
Yes. 14 sample questions are shown here in full, each with the correct option and a step-by-step "Why" explanation. Sign in free with Google to start practising, with instant scoring.
Is there negative marking in the "Cubes and Cube Roots" quizzes?+
Yes. The timed quizzes use exam-style marking: +4 for a right answer, −1 for a wrong one and 0 for a skip. MHT-CET and CBSE board papers have no negative marking. Our mocks for those are scored their way.
What are the important questions from Cubes and Cube Roots (Class 8 Mathematics)?+
The questions that matter most test Cube of a number, Perfect cube, Making a perfect cube, Cube root. This page shows 14 solved important MCQs with answers and explanations; all 72 questions on the chapter are available as timed quizzes once you sign in.
Is there an online quiz for Cubes and Cube Roots?+
Yes — Class 8 Mathematics Cubes and Cube Roots has timed online quizzes at Easy, Medium and Hard levels, with instant scoring and a worked explanation on every question. The first quiz on the chapter is free.