Class 8 Maths – Chapter 7
Cubes & Cube Roots

Very Important Questions (VSA / SA / LA)

✍️ Very Short Answer (1 Mark)

Q1. Find the cube of 4.

Ans: 4³ = 4 × 4 × 4 = 64

Q2. Find the cube root of 27.

Ans: ∛27 = 3

Q3. Is 125 a perfect cube?

Ans: Yes, because 5 × 5 × 5 = 125

Q4. Write the cube of −2.

Ans: (−2)³ = −8

✍️ Short Answer (2–3 Marks)

Q5. Find the cube root of 512.

Solution:

512 = 8 × 8 × 8

∛512 = 8

Q6. Check whether 343 is a perfect cube.

Solution:

343 = 7 × 7 × 7

Since factors are in groups of three, 343 is a perfect cube.

Q7. Find the cube of −6.

Solution:

(−6)³ = −6 × −6 × −6 = −216

✍️ Long Answer (4–5 Marks)

Q8. Find the smallest number by which 108 must be multiplied to get a perfect cube.

Solution:

Prime factorisation of 108:

108 = 2 × 2 × 3 × 3 × 3

We need one more pair of 2s.

Required number = 2 × 2 = 4

Q9. Find the cube root of 13824 by prime factorisation.

Solution:

13824 = 2³ × 3³

∛13824 = 2 × 3 = 24

🔥 HOTS / Application Question

Q10. Find the volume of a cube whose side is 7 cm.

Solution:

Volume of cube = side³

= 7³ = 343 cm³

📌 Examiner’s Tip

• Always show prime factorisation clearly
• Group factors in sets of three
• Underline the final answer

📘 Prepared by Shaktimatha Learning | CBSE Class 8