11.

The sum of first five prime numbers is:
A. 11 B. 18
C. 26 D. 28
Answer and Explanation
Answer: Option D
Explanation: Required sum = (2 + 3 + 5 + 7 + 11) = 28.

Note: 1 is not a prime number.

Definition: A prime number (or a prime) is a natural number that has exactly two distinct natural number divisors: 1 and itself.

12.

The difference of two numbers is 1365. On dividing the larger number by the smaller, we get 6 as quotient and the 15 as remainder. What is the smaller number ?

A. 240 B. 270
C. 295 D. 360
Answer and Explanation
Answer: Option B
Explanation: Let the smaller number be x. Then larger number = (x + 1365).

x + 1365 = 6x + 15

5x = 1350

x = 270

Smaller number = 270.

13.

72519 x 9999 = ?
A. 725117481 B. 674217481
C. 685126481 D. None of these
Answer and Explanation
Answer: Option A
Explanation: 72519 x 9999 = 72519 x (10000 - 1)

= 72519 x 10000 - 72519 x 1

= 725190000 - 72519

= 725117481.

14.

If the number 517 * 324 is completely divisible by 3, then the smallest whole number in the place of * will be:

A. 0 B. 1
C. 2 D. None of these
Answer and Explanation
Answer: Option C
Explanation: Sum of digits = (5 + 1 + 7 + x + 3 + 2 + 4) = (22 + x), which must be divisible by 3.

x = 2.

15.

The smallest 3 digit prime number is:
A. 103 B. 107
C. 113 D. None of these
Answer and Explanation
Answer: Option D
Explanation: The smallest 3-digit number is 100, which is divisible by 2.

100 is not a prime number.

√101< 11 and 101 is not divisible by any of the prime numbers 2, 3, 5, 7, 11.

101 is a prime number.

Hence 101 is the smallest 3-digit prime number.