If n is a 45-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 5
IV n is divisible by 45
Choose the correct option:  A) I only  B) I and II only  C) I and III only  D) I .II, III and IV only  E) I, II and III
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.   Rule for divisibility by 5: The sum of the digits of the number should be multiple of 5   Rules for divisibility by 45: The sum of the digits should a multiple of 45   Consider no 11111111...45 times = The sum 45*1= 
<gadget id="calculator">45*1</gadget>
<output>45</output>
45----&gt; divisbible by 3,9,5 and 45   consider number to be 222....45 times, then sum of the no. 45*2=90 divisibly by 3,9,5 and 45   So why so because when you sum the numbers either you can add the digits 45 times or multiply the digit *45..   Note that since 45 is divisble by 27,9 ,5 and 3 and thus the sum of the nos will be divisible by all the nos.   Ans is I .II, III and IV only
<result>D</result>
If n is a 45-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 5
IV n is divisible by 45