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 1511:00 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 1608:00 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. - Dec 21
11:00 AM IST
-01:00 PM IST
Do RC/MSR passages scare you? e-GMAT is conducting a masterclass to help you learn – Learn effective reading strategies Tackle difficult RC & MSR with confidence Excel in timed test environment
06 Aug 2003, 05:33
Kudos
Bookmarks
N
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
(N/A)
Question Stats:
0% (00:00) correct
0%
(00:00)
wrong
based on 0
sessions
History
Date
Time
Result
Not Attempted Yet
What is the units place of (A)^2A
1. A is not divisible by 5
2. Ais an even no.
1. A is not divisible by 5
2. Ais an even no.
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 Data Sufficiency (DS) 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!
06 Aug 2003, 08:38
Kudos
Bookmarks
B
My answer is 6. Crude method but still took me a minute.
From condition (1), A is not divisible by 5
for A=1, A^2A=1
for A=3, A^2A=3^6=3^3 * 3^3=27 * 27 => Unit's digit is 9
Hence, cond. (1) is not sufficient
From condition (1), A is even
for A=2, A^2A=2^4=16 => Unit's digit is 6
for A=4, A^2A=4^8= (4^2)^4=16^4 => Unit's digit is 6
for A=6, A^2A=6^12= (6^2)^6=36^6 => Unit's digit is 6
for A=8, A^2A=8^16= (8^2)^8=16^8 => Unit's digit is 6
Because the units digit is 6 before applying the power is 6 and the power is even, it has to give a 6 as the unit's digit in the final answer.
My answer is 6. Crude method but still took me a minute.
From condition (1), A is not divisible by 5
for A=1, A^2A=1
for A=3, A^2A=3^6=3^3 * 3^3=27 * 27 => Unit's digit is 9
Hence, cond. (1) is not sufficient
From condition (1), A is even
for A=2, A^2A=2^4=16 => Unit's digit is 6
for A=4, A^2A=4^8= (4^2)^4=16^4 => Unit's digit is 6
for A=6, A^2A=6^12= (6^2)^6=36^6 => Unit's digit is 6
for A=8, A^2A=8^16= (8^2)^8=16^8 => Unit's digit is 6
Because the units digit is 6 before applying the power is 6 and the power is even, it has to give a 6 as the unit's digit in the final answer.
06 Aug 2003, 08:51
Kudos
Bookmarks
(1) A is not divisible by 5
2^4=16, so the unit digit is 6
1^2=1; the units digit is 1, not suff
(2) A is even
2^4=16 --- 6
-2^-4=1/16 not even an integer
10^20 --- 0
not suff
Combine: 2^4=16, but -2^4 is not an integer, So it is E for the given verbiage.
If (2) were to be that A is positive and even, then the answer would be C.
Any even= 2N
(2N)^4N= (16*N^4)^N it will always have 6 as its last digits, save that N is a multiple of 5. 0^0 has no sense.
N^4
1^4=1 last digit is 1, does not affect 6
2^4=16, does not affect 6
3^4=81, does not affect 6
4^4=256, does not affect 6
5^4=625 DOES AFFECT 6
6^4 never affect 6
7^4=2401 does not affect 6
8^4=4096 does not affect 6
9^4=6561 does not affect 6
and so on
2^4=16, so the unit digit is 6
1^2=1; the units digit is 1, not suff
(2) A is even
2^4=16 --- 6
-2^-4=1/16 not even an integer
10^20 --- 0
not suff
Combine: 2^4=16, but -2^4 is not an integer, So it is E for the given verbiage.
If (2) were to be that A is positive and even, then the answer would be C.
Any even= 2N
(2N)^4N= (16*N^4)^N it will always have 6 as its last digits, save that N is a multiple of 5. 0^0 has no sense.
N^4
1^4=1 last digit is 1, does not affect 6
2^4=16, does not affect 6
3^4=81, does not affect 6
4^4=256, does not affect 6
5^4=625 DOES AFFECT 6
6^4 never affect 6
7^4=2401 does not affect 6
8^4=4096 does not affect 6
9^4=6561 does not affect 6
and so on
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 Data Sufficiency (DS) 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!
