Problems on Numbers Quiz Set 019

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Question 1

What is the digit at units place: 7020 × 8374 × 4473?

 A

0.

 B

1.

 C

3.

 D

2.

Soln.
Ans: a

The digit at units place = (last digit of 7020) × (last digit of 8374) × (last digit of 4473) = 0 × 4 × 3 = 0, which = 0.


Question 2

If  $x/3 = y/17 = z/22$, then ${x + y + z}/x$ = ?

 A

14.

 B

15.

 C

13.

 D

$5{2/3}$.

Soln.
Ans: a

Let $x/3 = y/17 = z/22$ = k. Then ${x + y + z}/x$ is same as ${3k + 17k + 22k}/{3k}$ which equals 14.

14 is same as 14.


Question 3

How many prime factors does 34650 have?

 A

7.

 B

8.

 C

6.

 D

9.

Soln.
Ans: a

We can see that $34650 = 2^1 × 3^2 × 5^2 × 7^1 × 11^1$. The number of prime factors is sum of the powers = 7.


Question 4

How many prime factors does 67500 have?

 A

9.

 B

10.

 C

8.

 D

11.

Soln.
Ans: a

We can see that $67500 = 2^2 × 3^3 × 5^4$. The number of prime factors is sum of the powers = 9.


Question 5

When a two digit number is reversed and added to itself we get 55. The product of the digits of that number is 6. What is the number?

 A

32.

 B

33.

 C

31.

 D

34.

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 55 = 11 × (a + b) ⇒ $a + b = 55 / 11 = 5$, so the digits are $a$ and $5 - a$. We are given their product as a × (5 - a) = 6, which is a quadratic expression that can be simplified to $(a - 3) × (2 - a) = 0$. So the number could be 32 or 23.


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Creative Commons License
This Blog Post/Article "Problems on Numbers Quiz Set 019" by Parveen (Hoven) is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Updated on 2017-04-07.

Posted by Parveen(Hoven),
Aptitude Trainer


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