• Varsity Tutors
    Award-winning private GMAT tutoring
    Register now and save up to $200

    Available with Beat the GMAT members only code

    MORE DETAILS
    Varsity Tutors
  • EMPOWERgmat Slider
    1 Hour Free
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    EMPOWERgmat Slider
  • Magoosh
    Magoosh
    Study with Magoosh GMAT prep

    Available with Beat the GMAT members only code

    MORE DETAILS
    Magoosh
  • The Princeton Review
    FREE GMAT Exam
    Know how you'd score today for $0

    Available with Beat the GMAT members only code

    MORE DETAILS
    The Princeton Review
  • Target Test Prep
    5-Day Free Trial
    5-day free, full-access trial TTP Quant

    Available with Beat the GMAT members only code

    MORE DETAILS
    Target Test Prep
  • PrepScholar GMAT
    5 Day FREE Trial
    Study Smarter, Not Harder

    Available with Beat the GMAT members only code

    MORE DETAILS
    PrepScholar GMAT
  • e-gmat Exclusive Offer
    Get 300+ Practice Questions
    25 Video lessons and 6 Webinars for FREE

    Available with Beat the GMAT members only code

    MORE DETAILS
    e-gmat Exclusive Offer
  • Veritas Prep
    Free Veritas GMAT Class
    Experience Lesson 1 Live Free

    Available with Beat the GMAT members only code

    MORE DETAILS
    Veritas Prep
  • Economist Test Prep
    Free Trial & Practice Exam
    BEAT THE GMAT EXCLUSIVE

    Available with Beat the GMAT members only code

    MORE DETAILS
    Economist Test Prep
  • Kaplan Test Prep
    Free Practice Test & Review
    How would you score if you took the GMAT

    Available with Beat the GMAT members only code

    MORE DETAILS
    Kaplan Test Prep

10! + 9! can be rewritten as:

This topic has 3 expert replies and 1 member reply
vinni.k Master | Next Rank: 500 Posts
Joined
17 Apr 2011
Posted:
389 messages
Followed by:
2 members
Upvotes:
6
Test Date:
2016
Target GMAT Score:
700+
GMAT Score:
620

10! + 9! can be rewritten as:

Post Wed Mar 07, 2018 8:11 am
10! + 9! can be rewritten as:

A. 9!(10)
B. 11!/10
C. (10!)^2*9
D. (9!)^2 + 10
E. 19!

OA is B

My approach
10! + 9!
10*9! + 9!
Taking out 9! common
9!(10 + 1)
9!(11)
Now from here i don't know how to proceed. So, i am bit stuck here. However, when i was reviewing, i played around with B
11!/10
(11 * 10 * 9!) / 10
(11)9!
Same outcome as what i got when i solved earlier, but how to get B on my first approach.

Thanks

  • +1 Upvote Post
  • Quote
  • Flag

GMAT/MBA Expert

Top Reply
Post Wed Mar 07, 2018 10:21 am
vinni.k wrote:
Brent@GMATPrepNow wrote:
You're almost there!

You have (11)9!
Check the answer choice.....(11)9! isn't there! So, we'll need to check each answer choice.

Thanks Brent,
So, the right approach for this question is to check each of the answer choices.
Once you've rewritten 10! + 9! as (11)9! and discovered that your answer is not among the answer choices, you can EITHER try to rewrite (11)9! so that it matches one of the answer choices, OR you can try to rewrite each answer choice so that it matches (11)9!.
The second option is most likely the faster approach.

Cheers,
Brent

_________________
Brent Hanneson – Creator of GMATPrepNow.com
Use our video course along with Beat The GMAT's free 60-Day Study Guide

Check out the online reviews of our course
Come see all of our free resources

  • +1 Upvote Post
  • Quote
  • Flag
GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMAT’s FREE 60-Day Study Guide and reach your target score in 2 months!

GMAT/MBA Expert

Top Reply
Post Wed Mar 07, 2018 9:05 am
vinni.k wrote:
10! + 9! can be rewritten as:

A. 9!(10)
B. 11!/10
C. (10!)^2*9
D. (9!)^2 + 10
E. 19!

OA is B

My approach
10! + 9!
10*9! + 9!
Taking out 9! common
9!(10 + 1)
9!(11)
Now from here i don't know how to proceed. So, i am bit stuck here. However, when i was reviewing, i played around with B
11!/10
(11 * 10 * 9!) / 10
(11)9!
Same outcome as what i got when i solved earlier, but how to get B on my first approach.

Thanks
You're almost there!

You have (11)9!
Check the answer choice.....(11)9! isn't there! So, we'll need to check each answer choice.

A. 9!(10)
We can clearly see that this is not equal to (11)9!
ELIMINATE A

B. 11!/10
11!/10 = (11)(10)(9)(8)(7)(6)(5)(4)(3)(2)(1)/(10)
= (11)(9)(8)(7)(6)(5)(4)(3)(2)(1)
= (11)(9!)
= B

Cheers,
Brent

_________________
Brent Hanneson – Creator of GMATPrepNow.com
Use our video course along with Beat The GMAT's free 60-Day Study Guide

Check out the online reviews of our course
Come see all of our free resources

  • +1 Upvote Post
  • Quote
  • Flag
GMAT Prep Now's comprehensive video course can be used in conjunction with Beat The GMAT’s FREE 60-Day Study Guide and reach your target score in 2 months!
vinni.k Master | Next Rank: 500 Posts
Joined
17 Apr 2011
Posted:
389 messages
Followed by:
2 members
Upvotes:
6
Test Date:
2016
Target GMAT Score:
700+
GMAT Score:
620
Post Wed Mar 07, 2018 9:32 am
Brent@GMATPrepNow wrote:
You're almost there!

You have (11)9!
Check the answer choice.....(11)9! isn't there! So, we'll need to check each answer choice.

Thanks Brent,
So, the right approach for this question is to check each of the answer choices.

  • +1 Upvote Post
  • Quote
  • Flag
Post Mon Mar 12, 2018 10:33 am
vinni.k wrote:
10! + 9! can be rewritten as:

A. 9!(10)
B. 11!/10
C. (10!)^2*9
D. (9!)^2 + 10
E. 19!
10! + 9! = 10 x 9! + 9! = 9!(10 + 1) = 9!(11) = 11!/10

Answer: B

_________________
Jeffrey Miller Head of GMAT Instruction

  • +1 Upvote Post
  • Quote
  • Flag

Top First Responders*

1 GMATGuruNY 111 first replies
2 Brent@GMATPrepNow 43 first replies
3 Rich.C@EMPOWERgma... 35 first replies
4 Jay@ManhattanReview 28 first replies
5 Scott@TargetTestPrep 11 first replies
* Only counts replies to topics started in last 30 days
See More Top Beat The GMAT Members

Most Active Experts

1 image description GMATGuruNY

The Princeton Review Teacher

157 posts
2 image description Brent@GMATPrepNow

GMAT Prep Now Teacher

141 posts
3 image description Scott@TargetTestPrep

Target Test Prep

104 posts
4 image description Jeff@TargetTestPrep

Target Test Prep

94 posts
5 image description Max@Math Revolution

Math Revolution

86 posts
See More Top Beat The GMAT Experts