Problems on Numbers Quiz Set 001

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. 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 2019-08-18.