Number System Questions for RRB Group-D Set-2 PDF
Download Top-14 RRB Group-D Number System Questions set-2 PDF. RRB GROUP-D Maths questions based on asked questions in previous exam papers very important for the Railway Group-D exam.
Download Number System Questions for RRB Group-D Set-2 PDF
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Question 1: What is the Lowest Common Factor of 81, 108 and 210?
a) 1
b) 3
c) 7
d) 9
Question 2: What is the HCF of 90, 135, 210?
a) 3
b) 6
c) 9
d) 15
Question 3: x and y are the smallest two digit prime numbers such that x = 2y + 1. What is the value of x – y?
a) 12
b) 18
c) 24
d) 30
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Question 4: What is the LCM of $7^5*8^6$, $7^3*8^4*9^2$ and $7^4*8^5*9$?
a) $7^3*8^4$
b) $7^3*8^4*9^3$
c) $7^5*8^6*9^2$
d) $7^6*8^7*9^3$
Question 5: What is HCF of 195, 390, 312 and 702?
a) 7
b) 13
c) 39
d) 65
Question 6: Which is the smallest number which when divided by 5,6 and 7 leaves a remainder of 2?
a) 212
b) 262
c) 282
d) 302
Question 7: Which of the following is NOT a prime number?
a) 43
b) 53
c) 71
d) 91
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Question 8: If the square root of 5.44802281 is 2.3341, what is the square root of 5448022.81?
a) 23341.1
b) 2334.1
c) 233.41
d) 23.341
Question 9: What is the HCF of 28, 42 and 56?
a) 0
b) 1
c) 7
d) None of the above
Question 10: What is the LCM of $3^2 * 2^3$, $4^2 * 3 * 2$ and $3^3 * 2 ^4$?
a) 864
b) 5184
c) 7776
d) 3888
Question 11: What is the Highest common factor of: 391, 483, 943 and 253?
a) 17
b) 19
c) 21
d) 23
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Question 12: What is the range of the following numbers?
19, 23, 17, 25, 18, 20, 20, 31, 16
a) 15
b) 18
c) 20
d) 22
Question 13: If 9765X is divisible by 11, what is the value of X?
a) 1
b) 3
c) 4
d) 8
Question 14: Which of the following numbers is NOT a multiple of 225?
2025, 2925, 5675, 6975
a) 2025
b) 2925
c) 5675
d) 6975
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Answers & Solutions:
1) Answer (A)
The lowest common factor of any set of natural numbers is 1. The Highest Common Factor of these three numbers is 3.
2) Answer (D)
90 = 3 * 3 * 2 * 5
135 = 5 * 3 * 3 * 3
210 = 2 * 5 * 3 * 7
So, 3 * 5 is the common factor of the three numbers.
3) Answer (A)
Since we are interested in the smallest two digit prime numbers, let’s start with the number 11.
If y = 11, x = 2 * 11 + 1 = 23, which is also a prime number.
So, the (x,y) set (23,11) satisfies the condition of 1) Prime numbers 2) Two digits 3) x = 2y + 1. So, the required answer is x – y = 23 – 11 = 12
4) Answer (C)
The numbers are $7^5*8^6$, $7^3*8^4*9^2$ and $7^4*8^5*9$.
Since, 7, 8, 9 are relatively prime, LCM of the given three numbers will contain the highest powers of 7,8,9 from all the given numbers.
Highest power of 7 is 5
Highest power of 8 is 6
Highest power of 9 is 2
So, LCM =$7^5*8^6*9^2$
5) Answer (C)
195 = 39 * 5
390 = 39 * 10
312 = 39 * 8
702 = 39 * 18
So, the HCF is 39
6) Answer (A)
The number is the LCM of 5,6 and 7 plus 2
So, 5 * 6 * 7 = 210 + 2 = 212
7) Answer (D)
91 = 7 * 13
8) Answer (B)
5448022.81 = 5.44802281 * $10^6$
So, $\sqrt{5.44802281 * 10^6}$ = 2.3341 * 1000 = 2334.1
9) Answer (D)
14 * 2 = 28
14 * 3 = 42
14 * 4 = 56
So, the Highest Common Factor of 28, 42 and 56 is 14.
10) Answer (A)
The numbers can be arranged as 3 * 24, 4 * 24, 18 * 24
So, 24 is common in all the three numbers.
So, the LCM = LCM( 3 , 4 ,18 ) * 24 = 36 * 24 = 864
11) Answer (D)
23 * 11 = 253
23 * 17 = 391
23 * 21 = 483
23 * 41 = 943
So, the HCF of the given numbers is 23
12) Answer (A)
The range of the numbers is given by the largest number – the smallest number = 31 – 16 = 15
13) Answer (D)
The divisibility test is that the sum of alternating numbers is divisible by 11.
So, 9 + 6 + x – 7 – 5 is divisible by 11
So, x has to be 8.
14) Answer (C)
225 * 9 = 2025
225 * 13 = 2925
225 * 31 = 6975
Only 5675 is not a multiple of 225
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