|
|
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.
Updated on: 13 Aug 2018, 02:04
Originally posted by EgmatQuantExpert on 27 Feb 2018, 10:17.
Last edited by EgmatQuantExpert on 13 Aug 2018, 02:04, edited 4 times in total.
Last edited by EgmatQuantExpert on 13 Aug 2018, 02:04, edited 4 times in total.
Kudos
Bookmarks
B
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
25%
(medium)
Question Stats:
75% (01:22) correct
25%
(01:20)
wrong
based on 484
sessions
History
Date
Time
Result
Not Attempted Yet
e-GMAT Question:
If \(M\) and \(x\) are positive integers greater than 1, what is the units digit of \(M^x\)?
(1) \(M\) when divided by \(5\) gives a remainder of \(1\).
(2) \(M = 21\)
A) Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B) Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C) BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D) EACH statement ALONE is sufficient.
E) Statements (1) and (2) TOGETHER are NOT sufficient
This is
Question 4 of The e-GMAT Number Properties Marathon
Go to
27 Feb 2018, 12:41
Kudos
Bookmarks
EgmatQuantExpert
1) m = 5k +2
m can be 2 or 7
insufficient as the unit digit varies
2) m =21
we know that 1^x unit digit is 1
sufficient
(B) imo
28 Feb 2018, 02:25
Kudos
Bookmarks
Solution:
Step 1: Analyse Statement 1:
\(X\), when divided by \(5\), leaves a remainder of \(2\).
- • Per our conceptual understanding, when a number is divided by \(5\), the remainder is equal to the units digit of the number (if the units digit is \(<5\)) and when the units digit is greater than \(5\), the remainder is: (Units digit -5).
- o Here, when \(M\) is divided by \(5\), the remainder is \(2\).
o Hence, the possible units digit of \(M\) can be \(2\) or \(7\).
Statement 1 alone is NOT sufficient to answer the question.
Hence, we can eliminate answer choices A and D.
Step 4: Analyse Statement 2:
\(X = 21\).
It is also given that “x” is a positive integer.
\(21^{Any Positive integer}\) will end with a \(1\) because \(1^{ Any positive integer}\) ends with a \(1\).
Since we could figure out the units digit of \(M^x\)
Statement 2 alone is SUFFICIENT to answer the question.
Step 5: Combine both Statements:
This step is not required since we already arrived at an answer from statement 2.
Correct Answer: Option B
