Problems on Numbers Quiz Set 001

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Question 1

What is 0.75757575...?

 A

$25/33$.

 B

$26/33$.

 C

$25/34$.

 D

$25/35$.

Soln.
Ans: a

0.75757575... is same as $0.\ov 75$. Let y = $0.\ov 75$. Multiply by 100, 100y = 75 + $0.\ov 75$ which is same as 75 + y. So 99y = 75, ⇒ y = $75/99$. So answer = ${25/33}$.


Question 2

When a two digit number is reversed and added to itself we get 143. The product of the digits of that number is 36. What is the number?

 A

49.

 B

50.

 C

48.

 D

51.

Soln.
Ans: a

Let the number be ab. When it is reversed and added to itself we get (10a + b) + (10b + a) = 11 × (a + b). We are given 143 = 11 × (a + b) ⇒ $a + b = 143 / 11 = 13$, so the digits are $a$ and $13 - a$. We are given their product as a × (13 - a) = 36, which is a quadratic expression that can be simplified to $(a - 4) × (9 - a) = 0$. So the number could be 49 or 94.


Question 3

The sum of three consecutive integer numbers is 696. The smallest of the three is?

 A

231.

 B

232.

 C

230.

 D

233.

Soln.
Ans: a

Let the numbers be n - 1, n and n + 1. The sum is 3n. We are given 3n = 696, ⇒ n = $696/3$, i.e., n = 232. So the smallest is 231.


Question 4

Which term of this arithmetic series is zero: 150, 140, 130 ...?

 A

16.

 B

17.

 C

15.

 D

18.

Soln.
Ans: a

The first term is 150, common difference is d = -10, n-th term is 0. So $0 = 150 + (n - 1) × -10$ which gives $n = 1 + {150/10} = 16$.


Question 5

How many prime factors does 16200 have?

 A

9.

 B

10.

 C

8.

 D

11.

Soln.
Ans: a

We can see that $16200 = 2^3 × 3^4 × 5^2$. The number of prime factors is sum of the powers = 9.


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This Blog Post/Article "Problems on Numbers Quiz Set 001" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2017-08-12.

Posted by Parveen(Hoven),
Aptitude Trainer


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