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.

These online tests are based on latest CBSE syllabus. While attempting these, our students can identify their weak lessons and continuously practice those lessons for attaining high marks. It also helps to revise the NCERT textbooks thoroughly


 

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.

Answer

Answer: (d)
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.

Answer

Answer: (c)
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.

Answer

Answer: (a)
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.

Answer

Answer: (c)
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.

Answer

Answer: (a)
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.

Answer

Answer: (b)
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.

Answer

Answer: (a)
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.

Answer

Answer: (a)
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.

Answer

Answer: (d)
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.

Answer

Answer: (d)
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.

Answer

Answer: (d)
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.

Answer

Answer: (b)
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.

Answer

Answer: (c)
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.

Answer

Answer: (b)
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.

Answer

Answer: (a)
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.

Answer

Answer: (b)
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.

Answer

Answer: (c)
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

Answer

Answer: (a)
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.

Answer

Answer: (a)
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.

Answer

Answer: (c)
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.

Answer

Answer: (b)
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.

Answer

Answer: (a)
Hint:
7 × 7 × 7 = 343.


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

Answer

Answer: (a)
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.

Answer

Answer: (a)
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.

Answer

Answer: (d)
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.

Answer

Answer: (a)
Hint:
Edge = \(\sqrt[3]{64}\) = \(\sqrt[3]{2 × 2 × 2 × 2 × 2 × 2}\)
= \(\sqrt[3]{2^3×2^3}\) = 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.

Answer

Answer: (b)
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.

Answer

Answer: (d)
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.

Answer

Answer: (a)
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.

Answer

Answer: (c)
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.

Answer

Answer: (a)
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.

Answer

Answer: (d)
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.

Answer

Answer: (b)
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.

Answer

Answer: (a)
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.

Answer

Answer: (a)
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.

Answer

Answer: (b)
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.

Answer

Answer: (b)
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.

Answer

Answer: (d)
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

Answer

Answer: (c)
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.

Answer

Answer: (c)
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.

Answer

Answer: (b)
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.

Answer

Answer: (b)
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.

Answer

Answer: (b)
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.

Answer

Answer: (a)
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.

Answer

Answer: (a)
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.

Answer

Answer: (c)
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.

Answer

Answer: (a)
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.

Answer

Answer: (b)
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.

Answer

Answer: (c)
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.

Answer

Answer: (d)
Hint:
4 × 4 × 4 = 64.


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