Register    Login    Search    Rss Feeds

Forums Home » Ask An Instructor » GMAT Math » Manhattan GMAT Math Strategy Guides


 Page 1 of 1 [ 2 posts ] 



  Print view Print view Previous topic Previous topic | Next topic Next topic
 

If r,s and t are consecutive positive multiples of 3....

Author Message
twmcgaffic
 Post subject: If r,s and t are consecutive positive multiples of 3....
 Post Posted: Thu May 21, 2009 11:03 am 
Offline
Students


Posts: 1
3rd ed. Number properties ch.4 p.87 #9

If r,s and t are consecutive positive multiples of 3. Is rst divisible by 27, 54, or both?

The answer currently states that the product of rst must have 3 3’s as factors and at least one 2. I agree, but wouldn’t the product also contain a fourth 3, because this is a set of 3 consecutive integers?

Thanks,

Tom
Top 
StaceyKoprince
 Post subject: Re: If r,s and t are consecutive positive multiples of 3....
 Post Posted: Thu May 28, 2009 2:12 pm 
Offline
ManhattanGMAT Staff


Posts: 6077
Location: San Francisco
Nice! Yes, you can say that three consecutive multiples of 3 must contain four 3's as factors. Two of the three consecutive numbers will contain at least one multiple of 3. One of the three consecutive numbers must also be a multiple of 9 (which occurs every 3rd multiple of 3), so that number will contribute at least two 3's as factors.

I assume that the explanation doesn't point this out because we don't need that info to solve - but it would be nice if the explanation mentioned it anyway! :)

It's great that you noticed this extra info - because this might come into play on an even harder question!

_________________
Stacey Koprince
Instructor
Director of Online Community
ManhattanGMAT
Top 
Display posts from previous:  Sort by  
 
 Page 1 of 1 [ 2 posts ] 





Who is online

Users browsing this forum: No registered users and 0 guests

 
 

 
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to: