Forum Home > GMAT > Quantitative > Problem Solving (PS)
Events & Promotions
|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Dec 1207:30 AM PST
-08:30 AM PST
Join the conversation to learn more about INSEAD vs LBS
Dec 1310:00 AM EST
-12:00 PM EST
Have you ever wondered how to score a PERFECT 805 on the GMAT? Meet Julia, a banking professional who used the Target Test Prep course to achieve this incredible feat. Julia's story is nothing short of an inspiration.
Dec 1410:00 AM EST
-12:00 PM EST
Think a 100% GMAT Verbal score is out of your reach? Target Test Prep will make you think again! Our course uses techniques such as topical study and spaced repetition to maximize knowledge retention and make studying simple and fun.
Dec 1411:00 AM IST
-01:00 PM IST
Attend this session to learn how to Deconstruct arguments, Pre-Think Author’s Assumptions, and apply Negation Test.- Dec 15
11:00 AM IST
-01:00 PM IST
Attend this free GMAT Algebra Webinar and learn how to master the most challenging Inequalities and Absolute Value problems with ease. - Dec 16
08:00 AM PST
-11:59 PM PST
GMAT Club 12 Days of Christmas is a 4th Annual GMAT Club Winter Competition based on solving questions. This is the Winter GMAT competition on GMAT Club with an amazing opportunity to win over $40,000 worth of prizes! - Dec 17
09:00 AM PST
-10:00 AM PST
Join Manhattan Prep instructor Whitney Garner for a fun—and thorough—review of logic-based (non-math) problems, with a particular emphasis on Data Sufficiency and Two-Parts. - Dec 18
10:00 AM PST
-11:00 AM PST
Here is the essential guide to securing scholarships as an MBA student! In this video, we explore the various types of scholarships available, including need-based and merit-based options.
01 Oct 2018, 04:55
Kudos
Bookmarks
A
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
35%
(medium)
Question Stats:
67% (01:54) correct
33%
(02:11)
wrong
based on 282
sessions
History
Date
Time
Result
Not Attempted Yet
If x is a positive integer, does the remainder, when \((7^x + 1)\) is divided by 100, have 0 as the units’ digit?
(1) x = 4n + 2, where n is a positive integer.
(2) x > 5
(1) x = 4n + 2, where n is a positive integer.
(2) x > 5
01 Oct 2018, 05:11
Kudos
Bookmarks
Bunuel
If x is a positive integer, does the remainder, when \((7^x + 1)\) is divided by 100, have 0 as the units’ digit?
(1) x = 4n + 2, where n is a positive integer.
(2) x > 5
(1) x = 4n + 2, where n is a positive integer.
(2) x > 5
CONCEPT: Remainder when any number is divided by hundred are the last two digits of the number e.g. 137 divided by 100 leaves 37 remainder and likewise 923 divided by 100 leaves 23 remainder etc
i.e. we only need to know if the unit digit of \((7^x + 1)\) is Zero or NOT
i.e. we need to know if \(7^x\) has unit digit 9 or not which is possible when \(x = 4a+2\) because cyclicity of 7 is 4 and \(7^2\) and \(7^6\) and \(7^10\) etc have unit digit 9
Statement 1: x = 4n + 2, where n is a positive integer.
i.e. \(7^x\) will always have unit digit 9 hence
SUFFICIENT
\(Statement 2: x > 5\)
x may be 6 or 7 etc. hence unit digit of \(7^x\) may or may not be 9 hence
NOT SUFFICIENT
Answer: Option A
16 Apr 2019, 19:16
Kudos
Bookmarks
Bunuel
If x is a positive integer, does the remainder, when \((7^x + 1)\) is divided by 100, have 0 as the units’ digit?
(1) x = 4n + 2, where n is a positive integer.
(2) x > 5
(1) x = 4n + 2, where n is a positive integer.
(2) x > 5
\((7^x + 1)\)
#1
x=4n+2
value of x will be even always ; x=2,6,10 at n=0,1,2
by cyclicity of 7 we know
7^1=7
7^2=9
7^3=3
7^4=1
so we see x= 2,6,10.. we get unit digit as 9 so 9+1 ;10 unit digit is always 0
#2
x > 5
not sufficient as value of unit digit of 7^x will vary
IMO A
