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

 It is currently 24 Aug 2016, 22:42

### 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

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# 99,999^2 - 1^2 =

Author Message
TAGS:

### Hide Tags

Intern
Joined: 10 Jan 2013
Posts: 9
Followers: 0

Kudos [?]: 4 [0], given: 19

### Show Tags

11 Feb 2013, 08:34
3
This post was
BOOKMARKED
00:00

Difficulty:

35% (medium)

Question Stats:

71% (01:53) correct 29% (01:33) wrong based on 147 sessions

### HideShow timer Statistics

99,999^2 - 1^2 =

A. 10^10 - 2
B. (10^5 – 2)^2
C. 10^4(10^5 – 2)
D. 10^5(10^4 – 2)
E. 10^5(10^5 – 2)
[Reveal] Spoiler: OA

Last edited by Bunuel on 11 Feb 2013, 08:38, edited 1 time in total.
Renamed the topic and edited the question.
Math Expert
Joined: 02 Sep 2009
Posts: 34420
Followers: 6252

Kudos [?]: 79420 [0], given: 10016

Re: 99,999^2 - 1^2 = [#permalink]

### Show Tags

11 Feb 2013, 08:39
4112019 wrote:
99,999^2 - 1^2 =

A. 10^10 - 2
B. (10^5 – 2)^2
C. 10^4(10^5 – 2)
D. 10^5(10^4 – 2)
E. 10^5(10^5 – 2)

99,999^2 - 1^2 =

A. 10^10 - 2
B. (10^5 – 2)^2
C. 10^4(10^5 – 2)
D. 10^5(10^4 – 2)
E. 10^5(10^5 – 2)

Apply $$a^2-b^2=(a+b)(a-b)$$:

$$99,999^2-1^2 =(99,999+1)(99,999-1)=10^5(10^5-1-1)=10^5(10^5-2)$$

Hope it's clear.
_________________
GMAT Club Legend
Joined: 09 Sep 2013
Posts: 11042
Followers: 509

Kudos [?]: 133 [0], given: 0

Re: 99,999^2 - 1^2 = [#permalink]

### Show Tags

13 Mar 2015, 03:44
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________
Senior Manager
Joined: 02 Dec 2014
Posts: 375
Location: Russian Federation
Concentration: General Management, Economics
WE: Sales (Telecommunications)
Followers: 0

Kudos [?]: 66 [0], given: 346

Re: 99,999^2 - 1^2 = [#permalink]

### Show Tags

09 Jul 2016, 04:20
(99,999)^2 - (1)^2 = (100,000 -1)^2 - (1)^2 = (100,000)^2 - 2*100,000 + 1-1=(10^5)^2 - 2*(10^5) = 10^10 - 2*(10^5)=10^5(10^5 - 2) Answer E
_________________

"Are you gangsters?" - "No we are Russians!"

Director
Joined: 18 Oct 2014
Posts: 906
Location: United States
GMAT 1: 660 Q49 V31
GPA: 3.98
Followers: 74

Kudos [?]: 150 [0], given: 64

Re: 99,999^2 - 1^2 = [#permalink]

### Show Tags

09 Jul 2016, 09:10
4112019 wrote:
99,999^2 - 1^2 =

A. 10^10 - 2
B. (10^5 – 2)^2
C. 10^4(10^5 – 2)
D. 10^5(10^4 – 2)
E. 10^5(10^5 – 2)

99,999^2 - 1^2

a^2-b^2= (a+b) (a-b)

(99,999+1) (99,999-1)
10^5 (99,998)

10^5 (10^5-2)
_________________

I welcome critical analysis of my post!! That will help me reach 700+

Re: 99,999^2 - 1^2 =   [#permalink] 09 Jul 2016, 09:10
Similar topics Replies Last post
Similar
Topics:
1 12 chairs are arranged in a row and are numbered 1 to 12. 3 15 Apr 2014, 01:47
OG 12 PS #157 5 26 Jul 2010, 17:56
2 OG 12.problem 130 10 05 Dec 2009, 15:20
34 If (12!^16-12!^8)/(12!^16+12!^4)=a, what is the unit's digit 17 14 Nov 2009, 00:49
6 1/(2 - \sqrt3) = ? 4 23 May 2008, 11:00
Display posts from previous: Sort by