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## Wednesday 24 February 2021

### CBSE Class 8 Maths - MCQ and Online Tests - Unit 7 - Cubes and Cube Roots

#### CBSE Class 8 Maths – MCQ and Online Tests –  Unit 7 – Cubes and Cube Roots

Every year CBSE students attend Annual Assessment exams for 6,7,8,9,11th standards. These exams are very competitive to all the students. So our website provides online tests for all the 6,7,8,9,11th standards’ subjects. These tests are also very effective and useful for those who preparing for any competitive exams like Olympiad etc. It can boost their preparation level and confidence level by attempting these chapter wise online tests.

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#### CBSE Class 8 Maths – MCQ and Online Tests – Unit 7 – Cubes and Cube Roots

Question 1.
What is the one’s digit in the cube root of the cube number 5832 ?
(a) 2
(b) 4
(c) 6
(d) 8.

Hint:
8 × 8 × 8 = 512.

Question 2.
Find the smallest number by which the number 121 must be multiplied to obtain a perfect cube.
(a) 7
(b) 9
(c) 11
(d) 5.

Hint:
121 = 11 × 11.

Question 3.
Find the smallest number by which the number 88 must be divided to obtain a perfect cube.
(a) 11
(b) 5
(c) 7
(d) 9.

Hint:
88 = 2 × 2 × 2 × 11 = 2³ × 11.

Question 4.
What is the one’s digit in the cube root of the cube number 6859 ?
(a) 7
(b) 8
(c) 9
(d) 6.

Hint:
9 × 9 × 9 = 729.

Question 5.
Which of the following numbers is not a cube number ?
(a) 10000
(b) 3125
(c) 64
(d) 729.

Hint:
10000 = 2 × 2 × 2 × 2 × 5 × 5 × 5 × 5.
= 24 × 54 = 2³ × 2 × 5³ × 5.

Question 6.
The cube of an odd natural number is
(a) even
(b) odd
(c) may be even, may be odd
(d) prime number.

Hint:
3 × 3 × 3 = 27 (odd).

Question 7.
The cube of an even natural number is
(a) even
(b) odd
(c) may be even, may be odd
(d) prime number.

Hint:
6 × 6 × 6 = 216 (even).

Question 8.
The one’s digit of the cube of the number 111 is
(a) 1
(b) 2
(c) 3
(d) 9.

Hint:
1 × 1 × 1 = 1.

Question 9.
The one’s digit of the cube of the number 242 is
(a) 2
(b) 4
(c) 6
(d) 8.

Hint:
2 × 2 × 2 = 8.

Question 10.
The one’s digit of the cube of the number 123 is
(a) 3
(b) 6
(c) 9
(d) 7.

Hint:
3 × 3 × 3 = 27.

Question 11.
The one’s digit of the cube of the number 144 is
(a) 1
(b) 2
(c) 3
(d) 4.

Hint:
4 × 4 × 4 = 64.

Question 12.
The one’s digit of the cube of the number 50 is
(a) 1
(b) 0
(c) 5
(d) 4.

Hint:
0 × 0 × 0 = 0.

Question 13.
The one’s digit of the cube of the number 326 is
(a) 2
(b) 3
(c) 6
(d) 4.

Hint:
6 × 6 × 6 = 216.

Question 14.
The one’s digit of the cube of the number 325 is
(a) 2
(b) 5
(c) 3
(d) 6.

Hint:
5 × 5 × 5 = 125.

Question 15.
The one’s digit of the cube of the number 347 is
(a) 3
(b) 4
(c) 7
(d) 1.

Hint:
7 × 7 × 7 = 343.

Question 16.
The one’s digit of the cube of the number 68 is
(a) 1
(b) 2
(c) 6
(d) 8.

Hint:
8 × 8 × 8 = 512.

Question 17.
The one’s digit of the cube of the number 249 is
(a) 2
(b) 4
(c) 9
(d) 1.

Hint:
9 × 9 × 9 = 729.

Question 18.
What is the one’s digit in the cube root of the cube number 1331 ?
(a) 1
(b) 2
(c) 3
(d) 4

Hint:
1 × 1 × 1 = 1.

Question 19.
What is the one’s digit in the cube root of the cube number 1000000 ?
(a) 0
(b) 1
(c) 2
(d) 9.

Hint:
0 × 0 × 0 = 0.

Question 20.
What is the one’s digit in the cube root of the cube number 3375 ?
(a) 2
(b) 3
(c) 5
(d) 4.

Hint:
5 × 5 × 5 = 125.

Question 21.
What is the one’s digit in the cube root of the cube number 4096 ?
(a) 2
(b) 6
(c) 4
(d) 9.

Hint:
6 × 6 × 6 = 216.

Question 22.
What is the one’s digit in the cube root of the cube number 4913 ?
(a) 7
(b) 9
(c) 3
(d) 6.

Hint:
7 × 7 × 7 = 343.

Question 23.
Which of the following numbers is a perfect cube ?
(a) 125
(b) 36
(c) 75
(d) 100.

Hint:
125 = 5 × 5 × 5 = 5³.

Question 24.
Which of the following numbers is a cube number ?
(a) 1000
(b) 400
(c) 100
(d) 600.

Hint:
1000 = 10 × 10 × 10 = 10³.

Question 25.
Which of the following numbers is not a perfect cube ?
(a) 1331
(b) 512
(c) 343
(d) 100.

Hint:
100 = 2 × 2 × 5 × 5 = 2² × 5².

Question 26.
The volume of a cube is 64 cm³. The edge of the cube is
(a) 4 cm
(b) 8 cm
(c) 16 cm
(d) 6 cm.

Hint:
Edge = $$\sqrt{64}$$ = $$\sqrt{2 × 2 × 2 × 2 × 2 × 2}$$
= $$\sqrt{2^3×2^3}$$ = 2 × 2 = 4.

Question 27.
Apala makes a cuboid of plasticine of sides 5 cm, 4 cm, 2 cm. How many such cuboids will be needed to form a cube ?
(a) 20
(b) 25
(c) 10
(d) 16.

Hint:
Volume = 5 × 4 × 2 = 5 × 2 × 2 × 2
= 5 × 2³.

Question 28.
Which of the following is false ?
(a) Cube of any odd number is odd
(b) A perfect cube does not end with two zeroes
(c) The cube of a single digit number may be a single digit number
(d) There is no perfect cube which ends with 8.

Hint:
1728 = 12³.

Question 29.
What is the one’s digit in the cube root of the cube number 8000 ?
(a) 0
(b) 2
(c) 4
(d) 8.

Hint:
0 × 0 × 0 = 0.

Question 30.
The number of zeroes at the end of the cube of the number 20 is
(a) 1
(b) 2
(c) 3
(d) 6.

Hint:
? Number of zeroes at the end of the number 20 = 1
? Number of zeroes at the end of its cube = 3 × 1 = 3.

Question 31.
The number of zeroes at the end of the cube root of the cube number 1000 is
(a) 1
(b) 2
(c) 3
(d) 4.

Hint:
? Number of zeroes at the end of the cube = 3
? Number of zeroes at the end of the cube root = $$\frac{3}{3}$$ = 1.

Question 32.
The number of zeroes at the end of the cube of the number 100 is
(a) 1
(b) 2
(c) 4
(d) 6.

Hint:
? Number of zeroes at the end of the number 100 = 2
? Number of zeroes at the end of its cube = 3 × 2 = 6.

Question 33.
The number of zeroes at the end of the cube root of the cube number 8000000 is
(a) 1
(b) 2
(c) 3
(d) 6.

Hint:
? Number of zeroes at the end of the cube = 6
? Number of zeroes at the end of the cube root = $$\frac{6}{3}$$ = 2.

Question 34.
Find the smallest number by which the number 108 must be multiplied to obtain a perfect cube.
(a) 2
(b) 3
(c) 4
(d) 5.

Hint:
108 = 2 × 2 × 3 × 3 × 3 = 2 × 2 × 3³.

Question 35.
Find the smallest number by which the number 250 must be divided to obtain a perfect cube.
(o) 2
(b) 3
(c) 4
(d) 5.

Hint:
250 = 5 × 5 × 5 × 2 = 5³ × 2.

Question 36.
Find the smallest number by which the number 72 must be multiplied to obtain a perfect cube.
(a) 2
(b) 3
(c) 4
(d) 6.

Hint:
72 = 2 × 2 × 2 × 3 × 3 = 2³ × 3 × 3.

Question 37.
Find the smallest number by which the number 375 must be divided to obtain a perfect cube.
(a) 2
(b) 3
(c) 5
(d) 4.

Hint:
375 = 3 × 5 × 5 × 5 = 3 × 5³.

Question 38.
Find the smallest number by which the number 100 must be multiplied to obtain a perfect cube.
(a) 5
(b) 2
(c) 4
(d) 10.

Hint:
100 = 2 × 2 × 5 × 5.

Question 39.
Find the smallest number by which the number 10000 must be divided to obtain a perfect cube.
(a) 2
(b) 5
(c) 10
(d) 100

Hint:
10000 = 2 × 2 × 2 × 2 × 5 × 5 × 5 × 5
= 2³ × 2 × 5³ × 5.

Question 40.
Find the smallest number by which the number 200 must be multiplied to obtain a perfect cube.
(a) 2
(b) 10
(c) 5
(d) 100.

Hint:
200 = 2 × 2 × 2 × 5 × 5 = 2³ × 5 × 5.

Question 41.
Find the smallest number by which the number 625 must be divided to obtain a perfect cube.
(a) 3
(b) 5
(c) 25
(d) 125.

Hint:
625 = 5 × 5 × 5 × 5 = 5³ × 5.

Question 42.
Find the smallest number by which the number 128 must be multiplied to obtain a perfect cube.
(a) 2
(b)4
(c) 3
(d) 8.

Hint:
128 = 2 × 2 × 2 × 2 × 2 × 2 × 2
= 2³ × 2³ × 2.

Question 43.
Find the smallest number by which the number 256 must be divided to obtain a perfect cube.
(a) 2
(b) 4
(c) 8
(d) 16.

Hint:
256 = 2 × 2 × 2 × 2 × 2 × 2 × 2 × 2
= 2³ × 2³ × 2 × 2.

Question 44.
Find the smallest number by which the number 36 must be multiphed to obtain a perfect cube.
(a) 6
(b) 2
(c) 3
(d) 4.

Hint:
36 = 2 × 2 × 3 × 3.

Question 45.
Find the smallest number by which the number 1296 must be divided to obtain a perfect cube.
(a) 6
(b) 2
(c) 4
(d) 3.

Hint:
1296 =2 × 2 × 2 × 2 × 3 × 3 × 3 × 3
= 2³ × 2 × 3³ × 3.

Question 46.
Find the smallest number by which the number 392 must be multiplied to obtain a perfect cube.
(a) 3
(b) 5
(c) 7
(d) 6.

Hint:
392 = 2 × 2 × 2 × 7 × 7 = 2³ × 7 × 7.

Question 47.
Find the smallest number by which the number 2401 must be divided to obtain a perfect cube.
(a) 7
(b) 6
(c) 5
(d) 9.

Hint:
2401 = 7 × 7 × 7 × 7 = 7³ × 7.

Question 48.
What is the one’s digit in the cube root of the cube number 1728 ?
(a) 1
(b) 2
(c) 3
(d) 9.

Hint:
2 × 2 × 2 = 8.

Question 49.
What is the one’s digit in the cube root of the cube number 2197 ?
(a) 1
(b) 2
(c) 3
(d) 7.

Hint:
3 × 3 × 3 = 27.

Question 50.
What is the one’s digit in the cube root of the cube number 2744 ?
(a) 1
(b) 2
(c) 3
(d) 4.

Hint:
4 × 4 × 4 = 64.

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