This set of Class 8 Maths Chapter 7 Multiple Choice Questions & Answers (MCQs) focuses on “Cube Root of a Cube Number”.

1. Find cube root of 91125.

a) 35

b) 45

c) 55

d) 57

View Answer

Explanation: We can find cube root of number by estimation if we know for certain that cube root of number is natural number. Start making group of 3 digits from right. Thus, we get 91 and 125. Cube root of 125 is 5 which forms the unit place. 91 lies between 64 and 125. Hence, we would consider it to be 4 which forms tens place. Hence, cube root of 91125 is 45.

2. Find cube root of 6859.

a) 17

b) 18

c) 19

d) 20

View Answer

Explanation: We can find cube root of number by estimation if we know for certain that cube root of number is natural number. Start making group of 3 digits from right. Thus, we get 6 and 859. Cube root of 859 would have unit place 9 as unit place of 859 is 9. 6 lies between 1 and 8. Cube root of 6 would like between 1 and 2. Hence, we would consider it to be 1 which forms tens place. Hence, cube root of 6859 is 19.

3. Find cube root of 19683.

a) 27

b) 37

c) 47

d) 57

View Answer

Explanation: We can find cube root of number by estimation if we know for certain that cube root of number is natural number. Start making group of 3 digits from right. Thus, we get 19 and 683. Cube root of 683 would have unit place as 7 because 683 has unit place as 3. 19 lies between 8 and 27. Hence, we would consider it to be 2 which forms tens place. Hence, cube root of 19683 is 27.

4. Find cube root of 42875.

a) 25

b) 57

c) 55

d) 35

View Answer

Explanation: We can find cube root of number by estimation if we know for certain that cube root of number is natural number. Start making group of 3 digits from right. Thus, we get 42 and 875. Cube root of 875 would have unit digit as 5. 42 lies between 27 and 64. Hence, we would consider it to be 3 which forms tens place. Hence, cube root of 42875 is 35.

5. Find cube root of 857375.

a) 85

b) 97

c) 95

d) 65

View Answer

Explanation: We can find cube root of number by estimation if we know for certain that cube root of number is natural number. Start making group of 3 digits from right. Thus, we get 857 and 375. Cube root of 375 would have unit digit as 5. 857 lies between 729 and 1000. Hence, we would consider it to be 9 which forms tens place. Hence, cube root of 857375 is 95.

6. What is the cube root of 216000?

a) 60

b) 70

c) 80

d) 90

View Answer

Explanation: We can find cube root of number by estimation if we know for certain that cube root of number is natural number. Start making group of 3 digits from right. Thus, we get 216 and 000. Cube root of 0 would have unit digit as 0. Cube root of 216 is 6 which would form tens place. Hence, the cube root of 216000 is 60.

7. Find cube root of 300763.

a) 27

b) 37

c) 67

d) 57

View Answer

Explanation: We can find cube root of number by estimation if we know for certain that cube root of number is natural number. Start making group of 3 digits from right. Thus, we get 300 and 763. Cube root of 763 has unit place as 7 as unit place of 763 is 3. 300 lies between 216 and 343. Hence, we would consider it to be 6 which forms tens place. Hence, cube root of 300763 is 67.

8. Evaluate \(\sqrt[3]{15625}\).

a) 35

b) 25

c) 45

d) 15

View Answer

Explanation: ∛x represents cube root of number x. We can find cube root of number by estimation if we know for certain that cube root of number is natural number. Start making group of 3 digits from right. Thus, we get 15 and 625. Cube root of 625 has unit place as 5 as unit place of 625 is 5. 15 lies between 8 and 27. Hence, we would consider it to be 2 which forms tens place. Hence, cube root of 15625 is 25.

9. Evaluate \(\sqrt[3]{9261}\).

a) 51

b) 21

c) 29

d) 39

View Answer

Explanation: ∛x represents cube root of number x. We can find cube root of number by estimation if we know for certain that cube root of number is natural number. Start making group of 3 digits from right. Thus, we get 9 and 261. Cube root of 261 has unit place as 1 as unit place of 261 is 1. 9 lies between 8 and 27. Hence, we would consider it to be 2 which forms tens place. Hence, the cube root of 9261 is 21.

10. Find cube root of 79507.

a) 45

b) 47

c) 95

d) 43

View Answer

Explanation: We can find cube root of number by estimation if we know for certain that cube root of number is natural number. Start making group of 3 digits from right. Thus, we get 79 and 507. Cube root of 507 would have unit digit as 3 as unit digit of 507 is 7. 79 lies between 64 and 125. Hence, we would consider it to be 4 which forms tens place. Hence, cube root of 79507 is 43.

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