Aptitude - Number System Online Quiz



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Following quiz provides Multiple Choice Questions (MCQs) related to Number System. You will have to read all the given answers and click over the correct answer. If you are not sure about the answer then you can check the answer using Show Answer button. You can use Next Quiz button to check new set of questions in the quiz.

Questions and Answers

Q 1 - What is the unit digit in 735 - 348?

A - 5

B - 7

C - 2

D - 1

Answer : C

Explanation

Unit digit in 735 = (74)8 x 73
= 1 x 3 = 3
Unit digit in 348 = (34)12
= 1
Therefore, unit digit in 735 - 348 = 3 - 1 = 2

Q 2 - Which of the numbers is exactly divisible by 11?

A - 415591

B - 6472

C - 3364

D - 413976

Answer : A

Explanation

Divisibility by 11: If the difference between the sum of digits at odd places and the sum of its digits at even places is either 0 or a number divisible by 11.
(9 + 5 + 4) - (1 + 5 + 1) = 11 i.e. exactly divisible by 11.
(7 + 6) - (2 + 3) is not divisible by 11.
(6 + 3) - (4 + 3) is not divisible by 11.
(7 + 3 + 4) - (6 + 9 +1) is not divisible by 11.

Q 3 - Which of the following is a prime number?

A - 7

B - 9

C - 12

D - 20

Answer : A

Explanation

7 as it has no positive divisors except 1.

Q 4 - How many natural numbers are there between 17 and 9 which are exactly divisible by 6?

A - 13

B - 15

C - 14

D - 16

Answer : A

Explanation

Numbers -> 18, 24, 30, ... , 90
A.P: a = 18, d = 6, l = 90
tn = a + (n-1)d
90 = 18 + (n-1)6
90 = 18 + 6n -6
n = 13

Q 5 - 6 + 15 + 24 + 33 + ... + 123 = ?

A - 903

B - 603

C - 752

D - 690

Answer : A

Explanation

a = 6, d = 9, l = 123
Let number of terms be n
123 = a + (n - 1)d
123 = 6 + (n - 1)9
123 = 9n - 9
n = 14
Sn = n2 (a + l)
= 142 (6 + 123)
= 7 x 129
= 903

Q 6 - What is the unit digit in 2137754 ?

A - 1

B - 3

C - 7

D - 9

Answer : D

Explanation

  unit digit in (2137)754 = unit digit in (7)754 = unit digit in (74)188 x 72 = unit digit in (1 x 49) = 9 Thus Unit digit in (2137)754 is 9.  

Q 7 - 1024 x 976 = y. What is y?

A - 999414

B - 999324

C - 999424

D - 999524

Answer : C

Explanation

  y =1024 x 976  = (1000 + 24) x (1000 - 24)  Now using formula (a+b)(a-b)=a2-b2  y = (1000)2 - (24)2  = 1000000 - 576  = 999424  

Q 8 - 1008 x 992 = y. What is y?

A - 900936

B - 999816

C - 969836

D - 999836

Answer : A

Explanation

  y = 1008 x 992     = (1000 + 8) x (1000 - 8)  Using formulae (a+b)(a-b) = a2 - b2  ∴ y =  (1000)2 - (8)2  = 1000000 - 64  = 999936  

Q 9 - Which of the following is the smallest 3 digit prime number?

A - 103

B - 107

C - 109

D - 101

Answer : D

Explanation

101. (11)2 *gt; 101 and 101 is not divisible by any of the following prime numbers 2,3,5 and 7.

Q 10 - x divides ((49)15 -1) completely. What is x?

A - 8

B - 14

C - 50

D - 51

Answer : A

Explanation

   (xn-1) is divisible by x+1 if x is an even number.  (49)15 - 1  = [(72)15 -1]  =(7)30 -1  which is divisible by 7+1 ,8.  



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