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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

Answer : D

Explanation

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

Q 2 - The sum of first 25 natural numbers is?

Answer : B

Explanation

S_n = (1 + 2 + 3 + 4 + ... + 25)
A.P -> a = 1, d = 1, n = 25 where n = terms
S_n = S₂₅ = ⁿ⁄₂[2a + (n-1)d]
= ²⁵⁄₂ [2 x 1 + (25 - 1) x 1]
= 25 x 13
= 325

Q 3 - The smallest prime number is?

Answer : C

Explanation

The smallest prime number is 2.

Q 4 - How many terms are there in the G.P 3, 6, 12, ... , 768?

Answer : B

Explanation

a = 3, r = ⁶⁄₂ = 2
Let number of terms = n
-> t_n = 768
-> 768 = ar^n-1
-> 768 = 3 x 2^n-1
-> ⁷⁶⁸⁄₃ = 2^n-1
-> 256 = 2^n-1
-> 2⁸ = 2^n-1
-> n = 9
Therefore number of terms = 9

Q 5 - If 653pq is divisible by 90, then (p + q) =?

Answer : A

Explanation

90 = 10 x 9
653pq is divisible by 10, so we can say that q = 0
Now,if 653p0 is divisible by 9.
So, (6 + 5 + 3 + p + 0) = (14 + p) is divisible by 9. So, p = 4.
Therefore, (p + q) = 4 + 0 = 4

Q 6 - Which of the following number divides 4⁶¹ + 4⁶² + 4⁶³ + 4⁶⁴ completely?

Answer : B

Explanation

  4⁶¹ + 4⁶² + 4⁶³ + 4⁶⁴  = 4⁶⁰ x (4¹ + 4² + 4³ + 4⁴)  = 4⁶⁰ x (4 + 16 + 64 + 256)  = 4⁶⁰ x 340  which is divisible by 10.

Q 7 - (45 + 46 + 47 + ... + 114 + 115) = ?

Answer : C

Explanation

  Using formula for sum of natural numbers  (1 + 2 + 3 +... + n) = (1/2)n(n+1)  (45 + 46 + 47 + ... + 114 + 115) = (1 + 2 + 3 +... + 115) - (1 + 2 + 3 + ... + 44)  = (1/2) x 115 x 116 - (1/2) x 44 x 45  = 115 x 58 - 22 x 45  = 6670 - 990  = 5680

Q 8 - 1506 x 1506 = y. What is y?

Answer : D

Explanation

  y = 1506 x 1506   = (1500 + 6) x (1500 + 6)  = (1500 + 6)^{2^{Using formulae (a+b)^{2^{= a^{2^{+ b^{2^{+ 2ab  ∴ y = (1500)^{2^{+ (6)^{2^{+ 2 x 1500 x 6  = 2250000 + 36 + 18000  = 2268036}}}}}}}}}}}}

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

Answer : D

Explanation

97. As all other numbers are divisible by 3.

Q 10 - if the sum of three consecutive odd numbers is 3 more than twice of the third. What is the largest number?

Answer : C

Explanation

  Let's the numbers be a, a + 2, a + 4  => (a + a + 2 + a + 4) =  [2 x (a + 4)] + 3  => 3a + 6 = 2a + 11  => a = 5   => largest number is 9

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