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

 It is currently 05 Dec 2019, 23:42

### 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

# If n is a two-digit number, in which n = x^y. If x + y < 8, and x and

Author Message
TAGS:

### Hide Tags

Math Expert
Joined: 02 Sep 2009
Posts: 59561
If n is a two-digit number, in which n = x^y. If x + y < 8, and x and  [#permalink]

### Show Tags

24 May 2019, 01:41
00:00

Difficulty:

55% (hard)

Question Stats:

62% (02:20) correct 38% (01:56) wrong based on 37 sessions

### HideShow timer Statistics

If n is a two-digit number, in which n = x^y. If x + y < 8, and x and y are positive integers greater than one, then the units digit of n could be which of the following?

I. 5
II. 6
III. 7

A. I only
B. II only
C. III only
D. I and III only
E. I, II and III
Manager
Joined: 29 Dec 2018
Posts: 60
Location: India
Schools: HBS '22, Wharton '22
Re: If n is a two-digit number, in which n = x^y. If x + y < 8, and x and  [#permalink]

### Show Tags

24 May 2019, 01:54
X+Y < 8

X=5 and Y=2
N= 5^2 = 25
So, units digit can be 5

X=4 and Y=2
N= 4^2 = 16
So, units digit can be 6

X=3 and Y=3
N=3^3 = 27
So, units digit can be 7

Hence, 5,6, and 7 can be the units digit.
Option E

Posted from my mobile device
Senior Manager
Joined: 10 Jan 2013
Posts: 308
Location: India
Concentration: General Management, Strategy
GPA: 3.95
Re: If n is a two-digit number, in which n = x^y. If x + y < 8, and x and  [#permalink]

### Show Tags

24 May 2019, 03:50
Bunuel wrote:
If n is a two-digit number, in which n = x^y. If x + y < 8, and x and y are positive integers greater than one, then the units digit of n could be which of the following?

I. 5
II. 6
III. 7

A. I only
B. II only
C. III only
D. I and III only
E. I, II and III

so I took numbers to solve this question.
since x+y < 8

took 5 and 2
$$5^2$$= 25
I is possible

took 2 and 4
$$2^4$$=16.. so II is also possible

ideally one should stop at this point because the only option that has I and II is E.

Just to double check, one can use 3 and 3
$$3^3$$ = 27

ISB School Moderator
Joined: 08 Dec 2013
Posts: 615
Location: India
Concentration: Nonprofit, Sustainability
Schools: ISB '21
GMAT 1: 630 Q47 V30
WE: Operations (Non-Profit and Government)
Re: If n is a two-digit number, in which n = x^y. If x + y < 8, and x and  [#permalink]

### Show Tags

24 May 2019, 08:38
Bunuel wrote:
If n is a two-digit number, in which n = x^y. If x + y < 8, and x and y are positive integers greater than one, then the units digit of n could be which of the following?

I. 5
II. 6
III. 7

A. I only
B. II only
C. III only
D. I and III only
E. I, II and III

n is a two digit number, let's see if we can form a two digit number by x^y when x+y<8

Let's try to get 5 in unit digit= 5^2, possible. 5+2<8
Let's try to get 6 in unit digit= 2^4, possible. 2+4<8
Let's try to get 7 in unit digit= 3^3, possible. 3+3<8
E, all I II and III possible.
Re: If n is a two-digit number, in which n = x^y. If x + y < 8, and x and   [#permalink] 24 May 2019, 08:38
Display posts from previous: Sort by