# Aptitude - Number System Online Quiz

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.

Q 1 - What is the result of the following?

` -82 x 39 + 235  `

A - 2963

B - 2960

C - 3963

D - 2963

### Explanation

= -82 x (40 - 1) + 235
= -(82 x 40) + 82 + 235
= -3280 + 317 = -2963

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

A - 415591

B - 6472

C - 3364

D - 413976

### 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 - The smallest prime number is?

A - 0

B - 1

C - 2

D - 3

### Explanation

The smallest prime number is 2.

Q 4 - 2 + 22 + 23 + ... + 211 = ?

A - 4094

B - 2048

C - 1012

D - 512

### Explanation

G.P: a = 2, r = 222 = 2, n = 11
Sn = a( rn - 1)(r - 1) = 2 x ( 211 - 1)(2 - 1) = 2 x (2048 - 1)
Therefore, Sn = 4094

Q 5 - A number when divided by 296 leaves 75 as remainder. When the same number is divided by 37, the remainder will be?

A - 3

B - 0

C - 1

D - 5

### Explanation

Lets x = 296q + 75 = (37 + 8q + 37 x 2) + 1
= 37 + (8q + 2) + 1
When the number is divided by 37, the remainder is 1.

Q 6 - What is the unit digit in in 7105?

A - 5

B - 7

C - 9

D - 1

### Explanation

` Unit digit in (7)105 = unit digit in (74)26 x 71 = unit digit in (1 x 7) = 7 Thus Unit digit in (7)105 is 7.`

Q 7 - 935421 x 625 = y. What is y?

A - 584638135

B - 584638145

C - 584638125

D - 584638115

### 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 - 14927 x 567 - 14927 x 467 = y. What is y?

A - 2985400

B - 1492700

C - 7463500

D - 7483500

### Explanation

`  y = 14927 x 567 - 14927 x 467   = 14927 x (567 - 467)   = 14927 x 100  = 1492700   `

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

A - 103

B - 107

C - 109

D - 101

### 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 - if a - b = 5 and a2 + b2 = 41, what is ab?

A - 5

B - 7

C - 8

D - 16

`  Using formulae (a-b)2 = a2 + b2 - 2ab  ab = (a2 + b2 - (a-b)2) / 2  => ab = [41 - (5)2] / 2  = 8  `