Number System : Aptitude Test (200 Questions with Explanation)

1.

What number should come next ?
173, 196, 219, 242, _____

   A.) 265
   B.) 267
   C.) 263
   D.) 264

Answer: Option 'A'

The given series is -- 173, 196, 219, 242
Consequtive numbers increases by 23
Following this pattern, the Missing Number should increase by 23 from the previous number.
When we add 23 to the last number (i.e 242) we get 242+23=265

2.

A professor wrote down the below series in a class room. He wants his students to find the Missing number. Can you solve it ?
112, 91, 70, X , 28, 7

   A.) 48
   B.) 47
   C.) 49
   D.) 51

Answer: Option 'C'

The given series is -- 112, 91, 70, X , 28, 7
Consequtive numbers decreases by 21
Following this pattern, the Missing Number X should decrease by 21 from the previous number.
When we subract 21 to the number before X (i.e 70) we get 70-21 = 49

3.

In a question on division with zero remainder, a candidate took 12 as divisor instead of 21. The quotient obtained by him was 35. The correct quotient is: 

   A.) 26
   B.) 25
   C.) 0
   D.) 20

Answer: Option 'D'

Number = (35 × 12) = 420 
Correct quotient = 420/21 = 20

4.

What is the least number to be added with 2016 to make it perfect square?

   A.) 16
   B.) 9
   C.) 11
   D.) 25

Answer: Option 'B'

452 = 2025, If we add 9 with 2016 we get 2025.

5.

Which one of the following is a prime number?

   A.) 119
   B.) 187
   C.) 551
   D.) None of these

Answer: Option 'D'

None of these

6.

If x and y are the two digits of the number 653xy such that this number is divisible by 80, then x + y = ?

   A.) 2 or 6
   B.) 4
   C.) 4 or 8
   D.) 8

Answer: Option 'A'

80 = 2 x 5 x 8 Since 653xy is divisible by 2 and 5 both, so y = 0. Now, 653x is divisible by 8, so 13x should be divisible by 8. This happens when x = 6. x + y = (6 + 0) = 6.

7.

What is the sum of all three digit numbers? 

   A.) 49550
   B.) 49455
   C.) 494450
   D.) 494550

Answer: Option 'D'

Sn = n/2[a + l] 
= 900/2 [100 + 999] 
= 450[1099] 
= 494550

8.

Cube root of (941192) = ?

   A.) 98
   B.) 108
   C.) 88
   D.) 7

Answer: Option 'A'

98 x 98 x 98 = 941192

9.

n is a whole number which when divided by 4 gives 3 as remainder. What will be the remainder when 2n is divided by 4?

   A.) 0
   B.) 1
   C.) 2
   D.) 3

Answer: Option 'C'

Let n = 4q + 3. Then 2n = 8q + 6 = 4(2q + 1 ) + 2. Thus, when 2n is divided by 4, the remainder is 2.

10.

By how much is 3/4th of 568 lesser than 7/8th of 1008

   A.) 476
   B.) 466
   C.) 456
   D.) 446

Answer: Option 'C'

7/8 × 1008=882 3/4 × 568=426 
so difference is 882-426=456

11.

Which natural number is nearest to 9217, which is completely divisible by 88?

   A.) 9152
   B.) 9240
   C.) 9064
   D.) 9184

Answer: Option 'B'

On dividing we get, 
88) 9217 (104 88 ---- 417 352 ---- 65 ---- Therefore, Required number = 9217 + (88 - 65) // Because (88 - 65) < 65. = 9217 + 23 = 9240.

12.

What least number must be added to 1056, so that the sum is completely divisible by 23 ?

   A.) 2
   B.) 3
   C.) 18
   D.) 21

Answer: Option 'A'

23) 1056 (45 92 --- 136 115 --- 21 --- 
Required number = (23 - 21) = 2.

13.

When a number is divided by 36, it leaves a remainder of 19. What will be the remainder when the number is divided by 12?

   A.) 10
   B.) 11
   C.) 7
   D.) 9

Answer: Option 'C'

Let the number be 'a'. When 'a' is divided by 36, let the quotient be 'q' and we know the remainder is 19. i.e., and remainder is 19 or a = 36q + 19 when 'a' is divided by 12, we get or . 36q is divisible by 12. Therefore, remainder = 7

14.

Find a number below 20 which can divide 19 and 22 perfectly?

   A.) 418
   B.) 2
   C.) 1
   D.) 3

Answer: Option 'C'

The fastest way to find the correct answer is by elimination rule :
Check whether each of the given choices divides both the numbers. If any of the given choices doesn't divide both the numbers, then you can eliminate that particular choice and move to the next choice. Answer will be the HIGHEST Number that exactly divides both given numbers.
1 is correct answer.
Please Note : There may be a scenario when two or more numbers in the choice will exactly divide both the numbers, in that case , please choose the Highest among the numbers.

15.

287 x 287 + 269 x 269 - 2 x 287 x 269 = ?

   A.) 534
   B.) 324
   C.) 446
   D.) 354

Answer: Option 'B'

Given Exp. = a2 + b2 - 2ab, where a = 287 and b = 269 = (a - b)2 = (287 - 269)2 = (182) = 324

16.

What is the sum of all two digit numbers? 

   A.) 4900
   B.) 4895
   C.) 4905
   D.) None of these

Answer: Option 'C'

10 + 11 + 12 + 13 + 14 + 15 + - - - - - - - - + 97 + 98 + 99 + 100 
Sn = n/2[a + l] 
= 90/2[10 + 99] 
= 45[109] 
= 4905.

17.

Find the value of k, if k / 171 = 76 / k

   A.) 114
   B.) 116
   C.) 124
   D.) 126

Answer: Option 'A'

k / 171 = 76 / k ? k2 = 76 x 171 = 4 x 19 x 19 x 9 ? k2=22 x 192 x 32 => k = 2 x 19 x 3 => k = 114

18.

On dividing a number by 5, we get 3 as remainder. What will the remainder when the square of the number is divided by 5

   A.) 0
   B.) 1
   C.) 2
   D.) 4

Answer: Option 'D'

Let the number be x and on dividing x by 5, we get k as quotient and 3 as remainder.
x = 5k + 3
x2 = (5k + 3)2
= (25k2 + 30k + 9)
= 5(5k2 + 6k + 1) + 4
On dividing x2 by 5, we get 4 as remainder.

19.

What should come in place of the question mark (?) in the following number series 2 5 11 23 47?

   A.) 94
   B.) 95
   C.) 97
   D.) 96

Answer: Option 'B'

2 5 11 23 47 ? It is clear that the next number has to be 47 + 48 =95

20.

The difference between the place values of two sevens in the numeral 69758472 is

   A.) 0
   B.) 699930
   C.) 6993
   D.) 699330

Answer: Option 'B'

Required difference = (700000 - 70) = 699930


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