Last visit was: 26 May 2026, 17:10 It is currently 26 May 2026, 17:10
Home
Messages
Tests
Schools
Events
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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
User avatar
toughmat
User avatar
Joined: 19 Apr 2011
Last visit: 13 Nov 2011
Posts: 58
Own Kudos:
12
Given Kudos: 2
Posts: 58
Kudos: 12
SQUARE of any two digit number - shortcut 01 Jun 2011, 06:05
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Good tip thanks for sharing



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Quantitative Questions Forum
Still interested in this question? Check out the "Best Topics" block below for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!
User avatar
bellcurve
User avatar
Joined: 19 Nov 2010
Last visit: 19 Mar 2014
Posts: 62
Own Kudos:
261
Given Kudos: 9
Posts: 62
Kudos: 261
SQUARE of any two digit number - shortcut 01 Jun 2011, 14:29
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Can you please explain how you 16+2 and 9+3?
avatar
arrypotter
avatar
Joined: 11 Aug 2007
Last visit: 02 Jun 2011
Posts: 2
Own Kudos:
4
Posts: 2
Kudos: 4
SQUARE of any two digit number - shortcut 01 Jun 2011, 20:54
Kudos
Add Kudos
Bookmarks
Bookmark this Post
bellcurve
Can you please explain how you 16+2 and 9+3?
Show more
Thanks mate for pointing, that is a wrong line. SOme typo there. Please exclude that line

9 | 16 + 2 |5 -- this is wrong (typo)


9 + 3 | 2 |5 - correct
User avatar
bellcurve
User avatar
Joined: 19 Nov 2010
Last visit: 19 Mar 2014
Posts: 62
Own Kudos:
261
Given Kudos: 9
Posts: 62
Kudos: 261
SQUARE of any two digit number - shortcut 02 Jun 2011, 06:02
Kudos
Add Kudos
Bookmarks
Bookmark this Post
This is a pretty cool trick. Thanks!
User avatar
AnkitK
User avatar
Joined: 11 Feb 2011
Last visit: 01 Dec 2012
Posts: 82
Own Kudos:
1,396
Given Kudos: 21
Posts: 82
Kudos: 1,396
SQUARE of any two digit number - shortcut 02 Jun 2011, 21:35
Kudos
Add Kudos
Bookmarks
Bookmark this Post
explain it for 29 pls
User avatar
puneetj
User avatar
Joined: 08 Sep 2010
Last visit: 21 Aug 2014
Posts: 69
Own Kudos:
91
Given Kudos: 18
Posts: 69
Kudos: 91
SQUARE of any two digit number - shortcut 11 Jun 2011, 09:15
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Numbers ending in 5 have a defined rule to square.
User avatar
IanStewart
User avatar
GMAT Tutor
Joined: 24 Jun 2008
Last visit: 25 May 2026
Posts: 4,147
Own Kudos:
11,337
 [1]
Given Kudos: 98
Location: United States
GMAT 1: 780 Q51 V47
Expert
Expert reply
GMAT 1: 780 Q51 V47
Posts: 4,147
Kudos: 11,337
 [1]
SQUARE of any two digit number - shortcut 11 Jun 2011, 09:29
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
arryputtar

29^2 how to solve this ?

Step 1: Identify the digits

29 - lets say "2" as "a" and "9" as b
So 2-> a and 9-> b

Step 2: Plug into the equation below
a^2 | 2(a*b) | b^2

instead of a -> use 2 and instead of b-> use 9

Step 3:

So by plugging in we get
2^2 | 2(2*9) | 9^2

Step 4:
solve the thing

2^2 => 4
2(2*9) => 36
9^2 => 81

4 | 36 | 81

Step 5:
this is the kewlest thing....all you need to do is carry over from right to left


4| 36 | 81 -> carry over 8 (left most digit just like addition)
4| 36 + 8 | 1 => 44 | 1
now from 44 carry over 4
4 + 4 | 4 | 1

8 | 4 |1 => 29 ^ 2 => 841
Show more

Fortunately we rarely (probably never) need to square awkward large numbers on the GMAT. If I need to find the value of 29^2, I'd take advantage of the difference of squares:

29^2 - 1 = (29 + 1)(29 -1) = (30)(28) = 840

so 29^2 = 841.

This would be a fast approach for a number ending in 9 or 1; for other numbers it would still lead to an awkward calculation.



Archived Topic
Hi there,
This topic has been closed and archived due to inactivity or violation of community quality standards. No more replies are possible here.
Where to now? Join ongoing discussions on thousands of quality questions in our Quantitative Questions Forum
Still interested in this question? Check out the "Best Topics" block above for a better discussion on this exact question, as well as several more related questions.
Thank you for understanding, and happy exploring!