 It is currently 24 Mar 2019, 13:08 ### 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

#### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here. # In sequence Q, the first number is 3, and each subsequent nu  Question banks Downloads My Bookmarks Reviews Important topics
Author Message
TAGS:
GRE Prep Club Legend  Joined: 07 Jun 2014
Posts: 4857
GRE 1: Q167 V156 WE: Business Development (Energy and Utilities)
Followers: 105

Kudos [?]: 1783 , given: 397

In sequence Q, the first number is 3, and each subsequent nu [#permalink]
Expert's post 00:00

Question Stats: 62% (00:31) correct 37% (01:50) wrong based on 8 sessions
In sequence Q, the first number is 3, and each subsequent number in the sequence is determined by doubling the previous number and then adding 2. In the first 10 terms of the sequence, how many times does the digit 8 appear in the units digit?

[Reveal] Spoiler: OA
9

_________________

Sandy
If you found this post useful, please let me know by pressing the Kudos Button

Try our free Online GRE Test

Director  Joined: 07 Jan 2018
Posts: 604
Followers: 7

Kudos [?]: 546 , given: 88

Re: In sequence Q, the first number is 3, and each subsequent nu [#permalink]
From the question stem:
The first term is 3
The second term is 3*2 + 2 = 8
The third term is 8*2 + 2 = 18

We can see that when the unit digit 8 is multiplied by 2 it ends with 6 and when 2 is added it becomes 8 hence all the terms except the first have their units digit as 8. In total there are 9 such terms
_________________

This is my response to the question and may be incorrect. Feel free to rectify any mistakes

GRE Prep Club Legend  Joined: 07 Jun 2014
Posts: 4857
GRE 1: Q167 V156 WE: Business Development (Energy and Utilities)
Followers: 105

Kudos [?]: 1783 , given: 397

Re: In sequence Q, the first number is 3, and each subsequent nu [#permalink]
Expert's post
Explanation

After the first term in the sequence, every term has a units digit of 8:

$$Q_1 = 3$$
$$Q_2 = 2(3) + 2 = 8$$
$$Q_3 = 2(8) + 2 = 18$$
$$Q_4 = 2(18) + 2 = 38$$
$$Q_5 = 2(38) + 2 = 78$$

So 8 is the units digit nine out of the first ten times.
_________________

Sandy
If you found this post useful, please let me know by pressing the Kudos Button

Try our free Online GRE Test Re: In sequence Q, the first number is 3, and each subsequent nu   [#permalink] 12 Aug 2018, 07:04
Display posts from previous: Sort by

# In sequence Q, the first number is 3, and each subsequent nu  Question banks Downloads My Bookmarks Reviews Important topics  Powered by phpBB © phpBB Group Kindly note that the GRE® test is a registered trademark of the Educational Testing Service®, and this site has neither been reviewed nor endorsed by ETS®.