GMAT Question of the Day - Daily to your Mailbox; hard ones only

 It is currently 14 Oct 2019, 03:44

### 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

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

# What is the units digits of N?

Author Message
TAGS:

### Hide Tags

e-GMAT Representative
Joined: 04 Jan 2015
Posts: 3074
What is the units digits of N?  [#permalink]

### Show Tags

Updated on: 31 Jan 2018, 22:56
00:00

Difficulty:

65% (hard)

Question Stats:

52% (01:47) correct 48% (01:28) wrong based on 63 sessions

### HideShow timer Statistics

Q.)

What is the units digits of N?

(I) The units digit of $$N^4$$ is $$6$$
(II) The units digit of$$(N - 2)^2$$ is $$6$$

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

_________________

Originally posted by EgmatQuantExpert on 31 Jan 2018, 06:19.
Last edited by EgmatQuantExpert on 31 Jan 2018, 22:56, edited 1 time in total.
e-GMAT Representative
Joined: 04 Jan 2015
Posts: 3074
Re: What is the units digits of N?  [#permalink]

### Show Tags

31 Jan 2018, 06:19
Retired Moderator
Joined: 22 Aug 2013
Posts: 1431
Location: India
Re: What is the units digits of N?  [#permalink]

### Show Tags

31 Jan 2018, 08:25
EgmatQuantExpert wrote:
Q.)

What is the units digits of N?

(I) The units digit of $$N^4$$ is $$6$$
(II) The units digit of$$(N - 2)^2$$ is $$6$$

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

(1) If units digit of N^4 is 6, then the unit digit of N could be 2 or 4 or 6 or 8 (all these even numbers have their fourth power ending in 6). So there is no single value for units digit of N. Not sufficient.

(2) If units digit of (N-2)^2 is 6, then the unit digit of (N-2) could be 4 or 6 (both 4 and 6 have their squares ending in 6). Now if (N-2) ends in 4, then N will end in 6 and if (N-2) ends in 6, then N will end in 8. Still two possibilities for units digit of N. Not sufficient.

Combining the two statements, units digit of N could still be 6 or 8. Still no unique value. Not sufficient.

Director
Joined: 31 Jul 2017
Posts: 512
Location: Malaysia
GMAT 1: 700 Q50 V33
GPA: 3.95
WE: Consulting (Energy and Utilities)
Re: What is the units digits of N?  [#permalink]

### Show Tags

31 Jan 2018, 09:34
EgmatQuantExpert wrote:
Q.)

What is the units digits of N?

(I) The units digit of $$N^4$$ is $$6$$
(II) The units digit of$$(N - 2)^2$$ is $$6$$

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

The numbers with their unit digit as 2, 4, 6 & 8 raised to power of 4 will have their unite digit as 6.

Statement I: Here, N = 2/4/6/8.... So, Insufficient.
Statement II: Here, N = 6/8..... So, Insufficient.

Combining the two statements we get... N = 6/8.

So, E.
_________________
If my Post helps you in Gaining Knowledge, Help me with KUDOS.. !!
Re: What is the units digits of N?   [#permalink] 31 Jan 2018, 09:34
Display posts from previous: Sort by