Number System : Aptitude Test (200 Questions with Explanation)

1.

Find the LCM of 25 , 3?

   A.) 75
   B.) 150
   C.) 48
   D.) 100

Answer: Option 'A'

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

2.

(35423 + 7164 + 41720) - (317 x 89) = ?

   A.) 28213
   B.) 56094
   C.) 84307
   D.) 50694

Answer: Option 'B'

35423 317 x 89 = 317 x (90 -1 ) + 7164 = (317 x 90 - 317) + 41720 = (28530 - 317) ----- = 28213 84307 - 28213 ----- 56094 -----

3.

Which number should come in place of the missing Number ?
112, 143, 174, X , 236, 267

   A.) 204
   B.) 203
   C.) 207
   D.) 205

Answer: Option 'D'

The given series is -- 112, 143, 174, X , 236, 267
Consequtive numbers increases by 31
Following this pattern, the Missing Number X should increase by 31 from the previous number.
When we add 31 to the number before X (i.e 174) we get 174+31=205

4.

If the number 653 xy is divisible by 90, then (x + y) = ?

   A.) 2
   B.) 3
   C.) 4
   D.) 6

Answer: Option 'C'

90 = 10 x 9 Clearly, 653xy is divisible by 10, so y = 0 Now, 653x0 is divisible by 9. So, (6 + 5 + 3 + x + 0) = (14 + x) is divisible by 9. So, x = 4. Hence, (x + y) = (4 + 0) = 4.

5.

If x and y are positive integers such that (3x + 7y) is a multiple of 11, then which of the following will be divisible by 11?

   A.) 4x - 9y
   B.) x + y + 4
   C.) 4x + 6y
   D.) 9x + 4y

Answer: Option 'A'

By hit and trial, we put x = 5 and y = 1 so that (3x + 7y) = (3 x 5 + 7 x 1) = 22, which is divisible by 11. Therefore, (4x + 6y) = ( 4 x 5 + 6 x 1) = 26, which is not divisible by 11; (x + y + 4 ) = (5 + 1 + 4) = 10, which is not divisible by 11; (9x + 4y) = (9 x 5 + 4 x 1) = 49, which is not divisible by 11; (4x - 9y) = (4 x 5 - 9 x 1) = 11, which is divisible by 11.

Number System Download Pdf