# Cubes and Cube Roots – Class 8/Worksheets.

**Chapter 7 of CBSE/NCERT Class 8 Maths is about Cubes and Cube roots. Here in this lesson you can find out practice problems of this chapter.**

**CBSE CLASS 8 MATHEMATICSCubes and Cube Roots – Chapter 7/ WorksheetsFill in the blanks:**

- Cube of odd numbers is always —————
- If a number ends in 0, its cube ends in ————
- Which number is known as Ramanujan Number————-?
- Cube root of 1 is ————–
- The one’s digit of the cube of 3331 is ————-

Answer the following: - Is 400 a perfect cube?
- Is 392 a perfect cube? If not, find the smallest natural number by which 392 must be multiplied so that the product is a perfect cube.
- Find the cube of the following numbers?

a) 20

b) 24 - Which of the following are cubes of even natural numbers?

a) 216

b) 343 - State true or false:

a) Cube of any odd number is even.

b) A perfect cube does not end with 2 zeros.

c). The cube root of 1 is 1 itself.

**ANSWERS:**

- Odd
- 0
- 1729
- 1
- 1
- We have 400 = 2 x 2 x 2 x 2 x 5 x 5

Here 2 and 5 are not in triplet.

Therefore, 400 is not a perfect cube. - We have 392 = 2 x 2 x 2 x7 x 7

The prime factor 7 does not appear in a group of three. Therefore, 392 is not a perfect cube. To make it’s a cube, we need one more 7.

In that case 392 x 7 = 2 x 2 x 2 x 7 x 7 x 7 = 2744, this is a perfect cube. - a) Cube of 20 = 20 x 20 x 20 = 8000

b)Cube of 24 = 24 x 24 x 24 = 13824 - a) 216 = 6 x 6 x 6, which is a cube of even natural numbers.

b) 343 = 7 x 7 x 7, which is a cube of odd natural numbers. - a) False

b) True

c) True