16.

Which one of the following numbers is exactly divisible by 11?

 A. 235641 B. 245642 C. 315624 D. 415624
Explanation: 415624 is exactly divisible by 11.

17.

(?) - 19657 - 33994 = 9999

 A. 63650 B. 53760 C. 59640 D. 61560
Explanation: 19657+33994=53651

Let x - 53651 = 9999

Then, x = 9999 + 53651 = 63650

18.

(?) + 3699 + 1985 - 2047 = 31111

 A. 34748 B. 27474 C. 30154 D. 27574
Explanation: x + 3699 + 1985 - 2047 = 31111

x + 3699 + 1985 = 31111 + 2047

x + 5684 = 33158

x = 33158 - 5684 = 27474.

19.

How many 3-digit numbers are completely divisible 6 ?

 A. 149 B. 150 C. 151 D. 166
Explanation: 3-digit number divisible by 6 are: 102, 108, 114,... , 996

This is an A.P. in which a = 102, d = 6 and l = 996

Let the number of terms be n. Then tn = 996.

a + (n - 1)d = 996

102 + (n - 1) x 6 = 996

6 x (n - 1) = 894

(n - 1) = 149

n = 150

Number of terms = 150.

20.

How many natural numbers are there between 23 and 100 which are exactly divisible by 6 ?

 A. 8 B. 11 C. 12 D. 13
Explanation: Required numbers are 24, 30, 36, 42, ..., 96

This is an A.P. in which a = 24, d = 6 and l = 96

Let the number of terms in it be n.

Then tn = 96a + (n - 1)d = 96

24 + (n - 1) x 6 = 96

(n - 1) x 6 = 72

(n - 1) = 12

n = 13

Required number of numbers = 13.