Cube Root Questions and Answers

This set of Aptitude Questions and Answers (MCQs) focuses on “Cube Root”.

1. Find the digit in the unit’s place in the square root of 198916.
a) 6
b) 2
c) 4
d) 8
View Answer

Answer: a
Explanation: The digit in the unit’s place in the square root of 198916 is 6.

2. How many perfect squares lie between 300 and 1000?
a) 15
b) 14
c) 12
d) 13
View Answer

Answer: b
Explanation: Perfect squares between 300 and 1000 are 324, 361, 400, 441, 484, 529, 576, 625, 676, 729, 784, 841, 900 and 961.
Hence, there are 14 perfect squares that lie between 300 and 1000.

3. A woman was born in the first half of the eighteenth century and was p years old in the year p2. In which year she was born?
a) 1716
b) 1736
c) 1722
d) 1708
View Answer

Answer: c
Explanation: Clearly 422 = 1764.
So, the woman is 42 years old in the year 1764.
Therefore, she was born in (1764-42) = 1722, which lies in the first half of eighteenth century.
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4. Find the value of n if \(\sqrt{5^n}\)=625.
a) 7
b) 6
c) 3
d) 8
View Answer

Answer: d
Explanation: \(\sqrt{5^n}\)=625=54.
5n=58.
Hence, n = 8.

5. What percentage of numbers from 51 to 100 have squares that end in the digit 1?
a) 20%
b) 10%
c) 1%
d) 25%
View Answer

Answer: a
Explanation: The numbers from 51 to 100 which has 1 in the unit digit in its square are, 51, 59, 61, 69, ……, 91, 99. There are 10 numbers out of 50.
Therefore, required percentage = \(\frac{10}{50}\)*100=20%.

6. How many 3-digit numbers satisfy the condition that the last digit of the square of 3-digit number is 3?
a) 10
b) 0
c) 20
d) 9
View Answer

Answer: b
Explanation: Square numbers either end with 1, 4, 5, 6, 9 or 0. No square numbers end with 3.
Therefore, 3-digit numbers satisfy the condition that the last digit of the square of 3-digit number is 3 is zero.

7. If \(\sqrt{(a-3)(b+2)}\)=11, a and b being positive integers less than 20, find the value of a and b.
a) 13, 8
b) 15, 10
c) 14, 9
d) 7, 19
View Answer

Answer: c
Explanation: 11 is a prime number and its square 121 is divisible by 11 or 1.
Since, a and b being positive integers less than 20, (a-3)=11 🡪 a = 14 and (b+2)=11 🡪 b = 9.
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8. Which one of the following numbers has rational square root?
a) 0.009
b) 0.016
c) 2.5
d) 0.04
View Answer

Answer: d
Explanation: \(\sqrt{0.009}\)=0.0948…,\(\sqrt{0.016}\)=0.1234…,\(\sqrt{2.5}\)=1.5811…and \(\sqrt{0.04}\)=0.2.
Therefore, 0.04 has rational square root.

9. If 23A4 is perfect square, then find the value of A.
a) 0
b) 2
c) 4
d) 6
View Answer

Answer: a
Explanation: 482 = 2304. Therefore, A = 0

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10. Find the smallest perfect square that is divisible by 5!.
a) 1600
b) 3600
c) 900
d) 2500
View Answer

Answer: b
Explanation: 5! = 120 = 5*4*3*2*1 = 22*2*3*5. To make it a perfect square, it should be multiplied by 2*3*5 i.e., 30. Hence, the smallest perfect square that is divisible by 5! is 120*30 = 3600.

To practice all aptitude questions, please visit “1000+ Quantitative Aptitude Questions”, “1000+ Logical Reasoning Questions”, and “Data Interpretation Questions”.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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