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 MATHEMATICS
Cubes and Cube Roots – Chapter 7/ Worksheets
Fill in the blanks:

1. Cube of odd numbers is always —————
2. If a number ends in 0, its cube ends in ————
3. Which number is known as Ramanujan Number————-?
4. Cube root of 1 is ————–
5. The one’s digit of the cube of 3331 is ————-
   Answer the following:
6. Is 400 a perfect cube?
7. 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.
8. Find the cube of the following numbers?
   a) 20
   b) 24
9. Which of the following are cubes of even natural numbers?
   a) 216
   b) 343
10. 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:

1. Odd
2. 0
3. 1729
4. 1
5. 1
6. 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.
7. 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.
8. a) Cube of 20 = 20 x 20 x 20 = 8000
   b)Cube of 24 = 24 x 24 x 24 = 13824
9. 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.
10. a) False
    b) True
    c) True