GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 27 Jun 2019, 02:05

Close

GMAT Club Daily Prep

Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized
for You

we will pick new questions that match your level based on your Timer History

Track
Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice
Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

Close

Request Expert Reply

Confirm Cancel

A positive integer is divisible by 9 if and only if the sum of its

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

 
Director
Director
avatar
G
Joined: 19 Oct 2013
Posts: 525
Location: Kuwait
GPA: 3.2
WE: Engineering (Real Estate)
GMAT ToolKit User
Re: A positive integer is divisible by 9 if and only if the sum of its  [#permalink]

Show Tags

New post 26 Oct 2018, 17:47
bigdady wrote:
A positive integer is divisible by 9 if and only if the sum of its digits is divisible by 9. If n is a positive integer, for which of the following values of k is \(25*10^n + k*10^{2n}\) divisible by 9?

(A) 9
(B) 16
(C) 23
(D) 35
(E) 47


In this question regardless of the value of n we will have units digit of 0

So we are concerned with how 2+5+k adds up to a number divisible by 9

if we take 2+5+4+7 = 18 a number divisible by 9.

E is the answer choice.
Director
Director
avatar
G
Joined: 29 Jun 2017
Posts: 740
Re: A positive integer is divisible by 9 if and only if the sum of its  [#permalink]

Show Tags

New post 27 Dec 2018, 21:51
bigdady wrote:
A positive integer is divisible by 9 if and only if the sum of its digits is divisible by 9. If n is a positive integer, for which of the following values of k is \(25*10^n + k*10^{2n}\) divisible by 9?

(A) 9
(B) 16
(C) 23
(D) 35
(E) 47



is this from official source.
this is hard. many person do it wrongly

because k*10^2n has at least 1 number more than 25*10^n, we know that the sume of the two number will be
K25*10^x
for exam ple if k=52
the sume will be
5225*10^n

ONLY THIS CASE HAPPEN, we can add the digit, and find the answer is E.
GMAT Club Bot
Re: A positive integer is divisible by 9 if and only if the sum of its   [#permalink] 27 Dec 2018, 21:51

Go to page   Previous    1   2   [ 22 posts ] 

Display posts from previous: Sort by

A positive integer is divisible by 9 if and only if the sum of its

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne