Number System Questions for RRB Group-D Set-3 PDF
Download Top-10 RRB Group-D Number System Questions set – 3 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-3 PDF
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Question 1: Sum of two positive integers is 15 and product of them is 50. What will be the L.C.M. of the numbers?
a) 50
b) 30
c) 40
d) 10
Question 2: If the product of the two numbers is 525 and L.C.M. of the numbers is 105, what will be the H.C.F. of the numbers?
a) 3
b) 4
c) 5
d) 6
Question 3: 14 is the HCF of two numbers ‘p’ and ‘q’, where 14 < p < q. What is the minimum values of (p,q)?
a) 42, 28
b) 28, 14
c) 14, 28
d) 28, 42
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Question 4: Find the greatest number that divides 82, 147 and 199 so as to leave the same remainder in each case.
a) 7
b) 11
c) 13
d) 17
Question 5: Find the largest 4 digit number that is divisible by 78.
a) 9996
b) 9988
c) 9976
d) 9984
Question 6: Find the remainder when $79^{79}+79$ is divided by 80.
a) 78
b) 1
c) 79
d) 2
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Question 7: The product of two numbers is 7920 and their HCF is 12. Find the number of pairs of such numbers possible.
a) 1
b) 2
c) 3
d) 4
Question 8: The sum of first 50 natural numbers is:
a) 1225
b) 1250
c) 1300
d) 1275
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Question 9: The largest 5 digit number divisible by 99 is
a) 99999
b) 99990
c) 99991
d) 99980
Question 10: How many numbers between 1 and 1000 is divisible by 9?
a) 111
b) 110
c) 108
d) 114
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Answers & Solutions:
1) Answer (D)
Let’s say one of the number is x, hence another number will be 15-x
Hence, their product will be = $15x – x^2 = 50$
So after solving the above equation, we will get numbers as 10 and 5 and their L.C.M. will be 10
2) Answer (C)
As we know that the product of the two numbers = (L.C.M. of the numbers)*(H.C.F. of the numbers)
Hence, 525 = 105*(H.C.F.)
H.C.F. = 5
3) Answer (D)
Let the two numbers be 14x and 14y, where x and y are co-prime.
x, y > 1. The least possible values of x and y are 2 and 3 respectively.
So, the value of p is 14*2 = 28 and the value of q is 14*3 = 42
4) Answer (C)
147 – 82 = 65
199 – 147 = 52
The HCF of these differences is the number that divides all the three numbers leaving the same remainder.
65 = 13 * 5
52 = 13 * 4
=> HCF = 13
Hence, 13 is the answer.
5) Answer (D)
78*10 = 780
78 * 3 = 234
On adding the above, we get 78 * 13 = 1014
=> 78 * 130 = 10140
78 * 2 = 156
On subtracting the above, we get 78 * 128 = 9984
=> 9984 is the answer.
6) Answer (A)
($79^{79}+79$ mod 80) can be written as ($(-1)^{79}+79$ mod 80)
= (-1 + 79) mod 80
= 78 mod 80
= 78
7) Answer (B)
Let the two numbers be 12x and 12y
12x*12y = 7920
xy = 55 = 5*11 = 55*1
The two numbers can be [(12*5),(12*11)],[(12*55),(12*1)]
8) Answer (D)
Sum of first n natural numbers = n(n+1)/2
Sum of first 50 natural numbers = 50*51/2 = 1275
9) Answer (B)
Largest 5 digit number is 99999. This number on division by 99 gives 9 as a remainder.
The largest 5 digit number is 99999-9 = 99990
10) Answer (A)
Smallest number divisible by 9 in the given range is 9
Largest number in the given range is 999 which is divisible by 9.
The series goes like this:9, 18, 27, 36, 45……,999
999 = 9+(n-1)9
9(n-1) = 999-9 = 990
n-1 = 110
n = 111
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We hope this Number System Questions set – 3 PDF for RRB Group-D Exam will be highly useful for your preparation.
