If n is a 18-digit positive integer, all of whose digits are the same, which of the following must be true?
I. n is divisible by 3
II. n is divisible by 9
III. n is divisible by 18 Select
A) I only
B) I , II and III only
C) I and III only
D) II and III only
E) II
Rule for divisibility by 3: The sum of the digits of the number should be multiple of 3   Rule for divisibility by 9: The sum of the nos digits of the number should be divisible by 9 or the number should be divisible by 3 two times.   Rules for divisibility by 18: The sum of the digits should a multiple of 18   Consider no 11111111...18 times = The sum 18*1= 
<gadget id="calculator">18*1</gadget>
<output>18</output>
18----&gt; divisbible by 3,9 and 18   consider number to be 222....18 times, then sum of the no. 18*2=36 divisibly by 3,9 and 18   So why so because when you sum the numbers either you can add the digits 27 times or multiply the digit *18..   Note that since 18 is divisble by 18,9 and 3 and thus the sum of the nos will be divisible by all the nos.   Ans is I , II and III only
<result>B</result>
If n is a 18-digit positive integer, all of whose digits are the same, which of the following must be true?
I. n is divisible by 3
II. n is divisible by 9
III. n is divisible by 18