Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 14 Sep 2014, 18:18

### 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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# What is the unit's digit of 7^75 + 6? a. 1 b. 3 c. 5 d. 7 e.

Author Message
TAGS:
Manager
Joined: 20 May 2006
Posts: 97
Followers: 0

Kudos [?]: 0 [0], given: 0

What is the unit's digit of 7^75 + 6? a. 1 b. 3 c. 5 d. 7 e. [#permalink]  10 Aug 2007, 18:23
1
This post was
BOOKMARKED
What is the unit's digit of 7^75 + 6?

a. 1
b. 3
c. 5
d. 7
e. 9

Intern
Joined: 10 Aug 2007
Posts: 30
Followers: 0

Kudos [?]: 1 [0], given: 0

My guess would be E) 9

The units' digit of the powers of seven follow the same pattern:

7^1 = 7
7^2 = 49
7^3 = 343
7^4 = 2401

7^5 = 16807

This pattern of four can be repeated in its entirety 18 times with a remainder of 3. The third units' digit in the series is 3 which if we add 6 to, we get 9.
Senior Manager
Joined: 29 Nov 2006
Posts: 321
Location: Orange County, CA
Followers: 1

Kudos [?]: 20 [0], given: 0

Agree with Entranced for reasons already mentioned.

Key these types of questions: find the repeating pattern for the digits (usually 4 or 5 different digits that repeat).

This one may trick a few who forget to add the 6.
Similar topics Replies Last post
Similar
Topics:
2 What is the unit's digit of 7^75 + 6 ? 7 14 Sep 2010, 11:58
2^(4-1)^2/ 2^(3-2)= a) 2^8 b) 2^7 c) 2^6 d) 2^5 e) 2^4 22 07 Jan 2009, 16:52
97 What is the last digit 3^{3^3} ? A. 1 B. 3 C. 6 D. 7 E. 9 69 23 Sep 2008, 06:17
Find is the last digit of 3^(3^3) ? A) 1 B) 7 C) 6 D) 3 E) 5 8 12 Nov 2005, 10:48
Display posts from previous: Sort by