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 - The unit digit in 7153 is?

A - 6

B - 0

C - 7

D - 1

Answer : C

Explanation

7153 = (74)38 x 7
Now, unit digit of (74)38 = 1
Therefore, unit digit of 7153 = 1 x 7
= 7

Q 2 - If the number 517 * 324 is completely divisible by 3, then the smallest whole number in place of * will be?

A - 0

B - 3

C - 1

D - 2

Answer : D

Explanation

For this:
= (5 + 1 + 7 + x + 3 + 2 +4)
= 22 + x
Now, 22 + x must be divisible by 3. So, for this x should be 2.
22 + 2 = 24 i.e. divisible by 3

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 - 12 + 22 + 32 + ... + 202 = ?

A - 872

B - 3920

C - 2870

D - 767

Answer : C

Explanation

As 12 + 22 + 32 + ... + n2 = 16 n (n + 1)(2n + 1)
Here, n = 20 -> Sum = 16 x 20 x 21 x 41
= 2870

Q 5 - Find the total number of prime factors in the product (14)13 x 73 x 92?

A - 35

B - 63

C - 23

D - 33

Answer : D

Explanation

= (2 x 2)13 x 73 x (3 x 3)3
= 226 x 73 x 34

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 - 935421 x 625 = y. What is y?

A - 584638135

B - 584638145

C - 584638125

D - 584638115

Answer : C

Explanation

  y = 935421 x 625  = 935421 x (5)4  = 935421 x (10/2)4  = (935421 x (10)4)/(2)4)  = 935421 x 10000 / 16  = 9354210000 / 16  = 584638125  

Q 8 - (64)2 - (36)2 = 20 x y. What is y?

A - 70

B - 120

C - 180

D - 140

Answer : D

Explanation

  (64)2 - (36)2 = 20 x y  Using formulae (a+b)(a-b) = a2 - b2  => (64 + 36)(64 - 36) = 20 x y  => 100 x 28 = 20 x y  => y = 5 x 28  = 140  

Q 9 - Which of the following is a prime number?

A - 81

B - 33

C - 93

D - 97

Answer : D

Explanation

97. As all other numbers are divisible by 3.

Q 10 - One number is twice the second number and thrice the third number. If average of numbers is 44. What is the number?

A - 90

B - 99

C - 45

D - 36

Answer : B

Explanation

  Let's have smallest number be a  Thus (a + 2a + 3a) / 3 = 44  => 4a / 3 = 44  => a = 33  => largest number = 3a = 99  



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