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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 - The unit digit in the product (536 x 764 x 358)?

Answer : C

Explanation

Unit Digit = Unit Digit in (6 x 4 x 8)
= 2

Q 2 - Which of the following numbers is completely divisible by 45?

Answer : C

Explanation

45 = 5 x 9
So, co-primes are 5 and 9
For divisibility, the unit digits must be 0 or 5 and sum of digits must be divisible by 9.
The unit digit of 2025 is 5 and sum of digits is divisible by 9
Therefore, 2025 is completely divisible by 45.

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

Answer : D

Explanation

Let number be p
Dividing p by 5, we get k as quotient and remainder as 3
p = 5k + 3 ->
p² = (5k + 3)² p = (25k² + 30k + 9)
p = 5 (5k² + 6k + 1) + 4
Therefore, we get 4 as remainder on dividing p² by 5.

Q 4 - 1² + 2² + 3² + ... + 20² = ?

Answer : C

Explanation

As 1² + 2² + 3² + ... + n² = ¹⁄₆ n (n + 1)(2n + 1)
Here, n = 20 -> Sum = ¹⁄₆ x 20 x 21 x 41
= 2870

Q 5 - 190 x 5⁴ = ?

Answer : D

Explanation

= 190 x (¹⁰⁄₂)⁴
= ^{190 x 10⁴}⁄_2⁴
= 118750

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

Answer : B

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 - 587 x 999 = y. What is y?

Answer : A

Explanation

  y = 587 x 999   = 587 x (1000 - 1)  = 587 x 1000 - 587  = 587000 - 587  = 586413

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

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