Find all School-related info fast with the new School-Specific MBA Forum

It is currently 21 Sep 2014, 20:23

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

Everything about Factorials on the GMAT

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:
Intern
Intern
avatar
Joined: 27 Mar 2014
Posts: 15
Followers: 0

Kudos [?]: 1 [0], given: 5

Re: Everything about Factorials on the GMAT [#permalink] New post 17 Apr 2014, 02:09
Bunuel wrote:
agavaqif wrote:
Very nice post, indeed.is there anything about factors of factorial?


Check the links in my signature below.

Thankss. Actually after writing this post I found necessery info from links in your profile. Thanks again
Intern
Intern
avatar
Joined: 20 May 2014
Posts: 40
Followers: 0

Kudos [?]: 1 [0], given: 1

Re: Everything about Factorials on the GMAT [#permalink] New post 11 Jun 2014, 12:18
How many zeros are in the end (after which no other digits follow) of 32!?

\frac{32}{5}+\frac{32}{5^2}=6+1=7. Notice that the denominators must be less than or equal to 32 also notice that we take into account only the quotient of division (that is \frac{32}{5}=6 not 6.4). Therefore, 32! has 7 trailing zeros.

The formula actually counts the number of factors 5 in n!, but since there are at least as many factors 2, this is equivalent to the number of factors 10, each of which gives one more trailing zero.
how come we divide 32 by 5?
Expert Post
Math Expert
User avatar
Joined: 02 Sep 2009
Posts: 23504
Followers: 3511

Kudos [?]: 26634 [0], given: 2714

Re: Everything about Factorials on the GMAT [#permalink] New post 11 Jun 2014, 13:13
Expert's post
sagnik2422 wrote:
How many zeros are in the end (after which no other digits follow) of 32!?

\frac{32}{5}+\frac{32}{5^2}=6+1=7. Notice that the denominators must be less than or equal to 32 also notice that we take into account only the quotient of division (that is \frac{32}{5}=6 not 6.4). Therefore, 32! has 7 trailing zeros.

The formula actually counts the number of factors 5 in n!, but since there are at least as many factors 2, this is equivalent to the number of factors 10, each of which gives one more trailing zero.
how come we divide 32 by 5?


Well, this is done according to the formula given there.
_________________

NEW TO MATH FORUM? PLEASE READ THIS: ALL YOU NEED FOR QUANT!!!

PLEASE READ AND FOLLOW: 11 Rules for Posting!!!

RESOURCES: [GMAT MATH BOOK]; 1. Triangles; 2. Polygons; 3. Coordinate Geometry; 4. Factorials; 5. Circles; 6. Number Theory; 7. Remainders; 8. Overlapping Sets; 9. PDF of Math Book; 10. Remainders; 11. GMAT Prep Software Analysis NEW!!!; 12. SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) NEW!!!; 12. Tricky questions from previous years. NEW!!!;

COLLECTION OF QUESTIONS:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS ; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
25 extra-hard Quant Tests

Get the best GMAT Prep Resources with GMAT Club Premium Membership

1 KUDOS received
Intern
Intern
avatar
Joined: 27 Aug 2014
Posts: 28
GMAT Date: 09-27-2014
Followers: 1

Kudos [?]: 3 [1] , given: 25

CAT Tests
Re: Everything about Factorials on the GMAT [#permalink] New post 27 Aug 2014, 05:05
1
This post received
KUDOS
2
This post was
BOOKMARKED
I don't know the proof but I thought this would be useful:

Where a and b are integers,

(a + b)! is divisible by a!.b!
Re: Everything about Factorials on the GMAT   [#permalink] 27 Aug 2014, 05:05
    Similar topics Author Replies Last post
Similar
Topics:
6 Everything about London Business School arundas 7 12 Dec 2010, 17:55
1 Everything About an IPO jb32 0 18 Jul 2008, 10:00
Virtually everything astronomers known about objects outside goalsnr 3 13 Jul 2008, 17:00
virtually everything astronomers known about objects outside karun_aggarwal 0 15 Apr 2005, 22:30
Display posts from previous: Sort by

Everything about Factorials on the GMAT

  Question banks Downloads My Bookmarks Reviews Important topics  

Go to page   Previous    1   2   3   4   [ 64 posts ] 



GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group and phpBB SEO

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.