  # Aptitude Questions : Number System Set 10

Hello Aspirants. Welcome to Online Quantitative Aptitude Section with explanation in AffairsCloud.com. Here we are creating question sample in Number System, which is common for all the competitive exams. We have included Some questions that are repeatedly asked in bank exams !!

Questions Penned by Yogit

1. The sum of the digits of a two-digit number is 6. If the digits are reversed, the number is decreased by 36. Find the number?
a) 15
b) 51
c) 24
d) 42
e) None of these
a + b = 6
(10a + b) – (10b +a) = 36, a – b = 4
We get a = 5 and b = 1
So number is 51

2. If the places of last two-digits of a three digit number are interchanged, a new number greater than the original number by 36 is obtained. What is the difference between the last two digits of that number?
a) 2
b) 3
c) 4
d) 7
e) None of these
Explanation :
let the number be 100a + 10b + c
(100a + 10b +c) – (100a + 10c +b) = 36
b – c = 4

3. A number when divided by 837 leaves a remainder of 79. What will be the remainder when the same number is divided by 31?
a) 11
b) 13
c) 15
d) 17
e) None of these
Explanation :
Number = 837*a + 79
when this number is divided by 31, it leaves remainder of 17 (837 is completely divisible)

4. The numerator of a rational number is 4 less than the denominator. If the numerator is increased by 15 and denominator is decreased by 4, we get 6. Find the rational number?
a) 1/5
b) 2/7
c) 3/7
d) 5/9
e) None of these
Explanation :
let the fraction is (p-4)/p
now, (p -4 + 15)/(p-4) = 6
we get p = 7
so fraction = 3/7

5. When a number is added to 20 percent of the second number, we get 150 percent of the second number. Find the ratio between the first and second number?
a) 13:9
b) 12:10
c) 13:10
d) 17:10
e) None of these
Explanation :
a + (20/100)*b = (150/100)*b
a:b = 13:10

6. Two different numbers when divided by same divisor leaves remainder 7 and 9 respectively. When their sum is divided by the same divisor remainder was 4. Find the divisor?
a) 11
b) 12
c) 13
d) 14
e) None of these
Explanation :
Let first number N1 = D*a + 7
and second number N2 = D*b + 9
N1 + N2 = (a+b)*D + 16
Remainder is 4, so D will be 12

7. A number gets reduced to its two-third when 24 is subtracted from it. Find one-eighth of the number?
a) 7
b) 8
c) 9
d) 10
e) None of these
Explanation :
a – 24 = 2a/3
we get a = 72
so one-eighth of the number = 72/8 = 9

8. Three numbers are in the ratio 4:3:5. If the difference between thrice the third number and the sum of first and second number is 64. Find the difference between the first and third number?
a) 4
b) 8
c) 12
d) 16
e) None of these
Explanation :
15x – (7x) = 64, we get x = 8
difference between first and third number = 5x – 4x = x = 8

9. One-fifth of a number when subtracted from one – third of the number gives 24. Find the square of the number.
a) 32400
b) 28900
c) 14400
d) 36100
e) None of these
Explanation :
a/3 – a/5 = 24
a = 180, so square = 32400

10. 25% of a number is 2 times 65% of another number. Find the ratio of the second no to the first number?
a) 13:5
b) 5:26
c) 7:13
d) 26:5
e) None of these