Last visit was: 03 Sep 2026, 15:26 It is currently 03 Sep 2026, 15:26
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.
Close
Request Expert Reply
Confirm Cancel
avatar
SidKan
Joined: 02 Oct 2016
Last visit: 09 Apr 2018
Posts: 20
Own Kudos:
4
 [1]
Given Kudos: 35
Products:
Posts: 20
Kudos: 4
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
JeffTargetTestPrep
User avatar
Target Test Prep Representative
Joined: 04 Mar 2011
Last visit: 05 Jan 2024
Posts: 2,973
Own Kudos:
Given Kudos: 1,646
Status:Head GMAT Instructor
Affiliations: Target Test Prep
Expert
Expert reply
Posts: 2,973
Kudos: 8,947
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
exc4libur
Joined: 24 Nov 2016
Last visit: 22 Mar 2022
Posts: 1,678
Own Kudos:
Given Kudos: 607
Location: United States
Posts: 1,678
Kudos: 1,494
Kudos
Add Kudos
Bookmarks
Bookmark this Post
User avatar
kiranbhasker
Joined: 22 Apr 2020
Last visit: 04 Jul 2022
Posts: 17
Own Kudos:
Given Kudos: 372
GPA: 3.5
Products:
Posts: 17
Kudos: 6
Kudos
Add Kudos
Bookmarks
Bookmark this Post
This is a method i picked up from solving similar questions and was posted by Bunuel and Karishma in another thread.

7^131 = (5+2)^131 = 5^131 + 2^131

5^131 when divided by 5 doesn't leave a remainder.

for 2^131, find cyclicity of 2 which is 4. Then divide 131 by 4 the remainder would be 3

this means 2^131 = 2^3 in the sense both have same units digits which is 8. now 8/5 = 3

This method has so far worked for me for many questions.
Thanks team.
User avatar
Basshead
Joined: 09 Jan 2020
Last visit: 07 Feb 2024
Posts: 899
Own Kudos:
Given Kudos: 431
Location: United States
Posts: 899
Kudos: 339
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Cyclicity of 7 is: 7, 9, 3, 1

When we divide 131 by 4 we get a remainder of 3. Therefore, the units digit of 7^131 is 3.

Dividing 3 by 5, we get remainder 3. Answer is D.
User avatar
Jihyo
Joined: 01 Apr 2021
Last visit: 06 Mar 2022
Posts: 52
Own Kudos:
Given Kudos: 166
Posts: 52
Kudos: 226
Kudos
Add Kudos
Bookmarks
Bookmark this Post
7^131=(5+2)^131

we have to find the remainder of 2^131 when divided by 5.
2^1 yields a remainder of 2 when divided by 5,
2^2 yields 4
2^3 yields 3
2^4 yields 1
2^5 yields 2
so with a pattern of 2^(4k+3) , we will get 3 as a remainder if divided by 5.
ANS: D

is my method correct ?
Bunuel VeritasKarishma
User avatar
Kinshook
User avatar
Major Poster
Joined: 03 Jun 2019
Last visit: 03 Sep 2026
Posts: 6,129
Own Kudos:
Given Kudos: 164
Location: India
GMAT 1: 690 Q50 V34
WE:Engineering (Transportation)
Products:
GMAT 1: 690 Q50 V34
Posts: 6,129
Kudos: 6,086
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Asked: If you divide 7^131 by 5, which remainder do you get?

7^131Mod5 = 49^65*7mod5 = (-1)^65*2mod5 = -2mod5 = 3

IMO D
User avatar
Crytiocanalyst
Joined: 16 Jun 2021
Last visit: 27 May 2023
Posts: 938
Own Kudos:
Given Kudos: 309
Posts: 938
Kudos: 215
Kudos
Add Kudos
Bookmarks
Bookmark this Post
blackcrow
If you divide 7^131 by 5, which remainder do you get?

A. 0
B. 1
C. 2
D. 3
E. 4

(7^2)^65 * 2
=> 4^64 *3
=> (16)^32 *3
=> 1^32 *3
=> 3

Therefore IMO D
User avatar
KarishmaB
Joined: 16 Oct 2010
Last visit: 02 Sep 2026
Posts: 16,634
Own Kudos:
81,144
 [1]
Given Kudos: 489
Location: Pune, India
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 16,634
Kudos: 81,144
 [1]
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Jihyo
7^131=(5+2)^131

we have to find the remainder of 2^131 when divided by 5.
2^1 yields a remainder of 2 when divided by 5,
2^2 yields 4
2^3 yields 3
2^4 yields 1
2^5 yields 2
so with a pattern of 2^(4k+3) , we will get 3 as a remainder if divided by 5.
ANS: D

is my method correct ?
Bunuel VeritasKarishma


Yes, it is.
Note that when dividing by 5, the units digit alone determines the remainder. Since cyclicity of units digit of both 7 and 2 is 4, we know without calculating that cyclicity of remainders will be 4 too. Hence we don't even need to use binomial in the first step.

Check these posts:
https://www.gmatclub.com/forum/veritas-prep-resource-links-no-longer-available-399979.html#/2015/1 ... questions/
https://www.gmatclub.com/forum/veritas-prep-resource-links-no-longer-available-399979.html#/2015/1 ... ns-part-2/
User avatar
MalachiKeti
Joined: 01 Sep 2024
Last visit: 27 Jan 2025
Posts: 123
Own Kudos:
Given Kudos: 99
Posts: 123
Kudos: 93
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Hi Bunuel if we had to solve this by negative remainder concept is the approach correct? Ik not recommended but just want to know

(7^131)/5
=Rem (7/5) *Rem( 7^130/5)
= 2 * Rem (49^65/5)
= 2 * Rem (50 - 1 )^65/5
= 2 * Rem (-1)^65/5
= 2 * Rem (-1)/5
= 2 * 4
= 8
= Rem (8/5)
= 3
User avatar
SRIVISHUDDHA22
Joined: 08 Jan 2025
Last visit: 19 Aug 2026
Posts: 120
Own Kudos:
Given Kudos: 371
Location: India
Schools: ISB '26
GPA: 9
Products:
Schools: ISB '26
Posts: 120
Kudos: 80
Kudos
Add Kudos
Bookmarks
Bookmark this Post
blackcrow
If you divide 7^131 by 5, which remainder do you get?

A. 0
B. 1
C. 2
D. 3
E. 4

Attachment:
GMAT-Club-Forum-21vrpqox.png
GMAT-Club-Forum-21vrpqox.png [ 206.29 KiB | Viewed 410 times ]
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 39,213
Own Kudos:
Posts: 39,213
Kudos: 1,156
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.
   1   2 
Moderator:
Math Expert
113098 posts