**Number System Questions for RRB NTPC Set-4 PDF**

Download RRB NTPC Top-10 Number System Questions Set-4 PDF. Questions based on asked questions in previous exam papers very important for the Railway NTPC exam.

Download Number System Questions for RRB NTPC Set-4 PDF

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**Question 1: **Find the least number which should be subtracted from 9999 so that the difference is exactly divisible by 16?

a) 15

b) 12

c) 14

d) 13

**Question 2: **The LCM and HCF of two numbers are 4284 and 32, respectively. If one of the numbers is 672, then the second number is;

a) 102

b) 64

c) 204

d) 92

**Question 3: **Let n be the number of different 5-digit numbers divisible by 4, with the digits 4, 5, 6, 7, 8 and 9, no digit being repeated in the numbers. What is the value of n?

a) 8

b) 24

c) 168

d) 192

**Question 4: **The LCM of 56, 84 and 112 is:

a) 210

b) 336

c) 420

d) 168

**Question 5: **The HCF of 42, 63 and 105 is:

a) 7

b) 630

c) 63

d) 21

**Question 6: **Three bells ring at intervals of 15, 30 and 45 minutes respectively. At what time will they

ring together again, if they rang simultaneously at 8.00 AM ?

a) 8.30 AM

b) 9.30 AM

c) 9.00 AM

d) 8.45 AM

**Question 7: **Find the least number that is divisible by 12, 18, 21, and 30

a) 1020

b) 1260

c) 1620

d) 1060

**Question 8: **Find the LCM of $ab^{2}c^{2}$, $a^{2}bc$ and $a^{3}b^{3}c^{2}$.

a) $abc$

b) $a^{2}b^{2}c^{2}$

c) $a^{3}b^{3}c^{2}$

d) $a^{3}b^{3}c^{3}$

**Question 9: **Find the largest two-digit prime number.

a) 91

b) 97

c) 93

d) 89

**Question 10: **What is the difference between the place and face values of ‘5’ in the number 3675149?

a) 4995

b) 5000

c) 495

d) 4990

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**Answers & Solutions:**

**1) Answer (A)**

$\frac{9999}{16} = 624\frac{15}{16}$

$\frac{15}{16}\times 16 = 15$

This 15 is needed to be subtracted from 9999 to get a number which is exactly divisible by 16

Option A is correct.

**2) Answer (C)**

HCF is 32

LCM is 4284

Let the other number be x

We know that HCF * LCM = produce of 2 numbers.

$32\times 4284 = 672 \times x$

$x =\frac{32\times4284}{672}$

$x = 204$

Option C is correct.

**3) Answer (C)**

**4) Answer (B)**

Find the prime factorization of 56,84,112

56 = 2 × 2 × 2 × 7 ………i)

84 = 2 × 2 × 3 × 7……….ii)

112= 2 × 2 × 2 ×2 ×7………iii)

Multiply each factor the greater number of times it occurs in steps i) , ii) or iii) above to find the lcm:

LCM = 2 × 2 × 2 × 2×3 × 7

=336

**5) Answer (D)**

42 = $ 2 \times 3 \times 7$

63 = $ 3 \times 3 \times 7$

105 = $ 3 \times 5 \times 7$

Taking the common factors, the HCF would be 21.

So , the answer would be option d)21.

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**6) Answer (B)**

Given that three bells rang at intervals of 15, 30 and 45 minutes respectively.

They will together ring again in 90 minutes (LCM of 15, 30, 45).

90 minutes = 01 : 30 hours

Then, After 8 : 00 AM, they will again ring together in 08 : 00 + 01 : 30 = 09 : 30 AM

**7) Answer (B)**

$12=2\times 2\times 3$

$18=2\times 3\times 3$

$21 =3\times 7$

$30 =2\times 3\times 5$

Select the common terms

LCM = $2\times 2\times 3\times 3\times 5\times 7$

= 1260

**8) Answer (C)**

$ab^{2}c^{2}$, $a^{2}bc$ and $a^{3}b^{3}c^{2}$.

LCM

$=(abc)\times(bc)\times(a)\times(ab)$

$=a^{3}b^{3}c^{2}$

**9) Answer (B)**

**10) Answer (A)**

Given number = 3675149

Face value of 5 = 5

Place value of 5 = 5000

difference between the place and face values of ‘5’ in the number 3675149= 5000-5 = 4995

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We hope this Top-10 Number System Questions Set-4 PDF for RRB NTPC exam will be highly useful for your Preparation.