Last visit was: 26 Apr 2026, 08:47 It is currently 26 Apr 2026, 08:47
Home
Messages
Tests
Schools
Events
Close
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
Your Progress

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.
Go to My Error Log Learn more
Close
Request Expert Reply
Confirm Cancel
Back to Forum
Create Topic
505-555 (Easy)|   Sequences|      
avatar
Asifpirlo
avatar
Joined: 10 Jul 2013
Last visit: 26 Jan 2014
Posts: 220
Own Kudos:
1,195
 [2]
Given Kudos: 102
Posts: 220
Kudos: 1,195
 [2]
How many numbers of this sequence of 342 numbers are odd? 10 Aug 2013, 12:30
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
00:00
Start Timer
Pause Timer
Resume Timer
Show Answer
Hide
Show
History
C
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!

Difficulty:

15% (low)

Question Stats:

75% (01:15) correct 25% (01:17) wrong based on 198 sessions

History

Date
Time
Result
Not Attempted Yet
How many numbers of this sequence of 342 numbers are odd?
(1) The sequence starts with -1,3,-3,..........
(2) Except for the 1st two numbers, every number in the sequence is the product of the two immediately preceding numbers

Show Spoiler
publishing soon :-D
ShowHide Answer
Official Answer
C
User avatar
blueseas
User avatar
Current Student
Joined: 14 Dec 2012
Last visit: 15 Jan 2019
Posts: 572
Own Kudos:
4,535
 [2]
Given Kudos: 197
Location: India
Concentration: General Management, Operations
Schools: PGDM (GM) '15 (A)
GMAT 1: 700 Q50 V34
GPA: 3.6
Schools: PGDM (GM) '15 (A)
GMAT 1: 700 Q50 V34
Posts: 572
Kudos: 4,535
 [2]
How many numbers of this sequence of 342 numbers are odd? 10 Aug 2013, 12:41
2
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Asifpirlo
How many numbers of this sequence of 342 numbers are odd?
(1) The sequence starts with -1,3,-3,..........
(2) Except for the 1st two numbers, every number in the sequence is the product of the two immediately preceding numbers

Show Spoiler
publishing soon :-D
Show more

statement 1:The sequence starts with -1,3,-3,..........
insufficient as we dont know what all numbers are there in this series.

statement 2:Except for the 1st two numbers, every number in the sequence is the product of the two immediately preceding numbers
insufficient as we dont know what are numbers in the series.

combining:
first two numbers are -1,3...now the following numbers will be multiple of previous 2 numbers ...
you can see both numbers are ODD....and we know\(ODD*ODD = ODD\)..So clearly following digits will be ODD.
Hence we can conclude that all numbers are odd
hence sufficient.
C
avatar
Asifpirlo
avatar
Joined: 10 Jul 2013
Last visit: 26 Jan 2014
Posts: 220
Own Kudos:
1,195
Given Kudos: 102
Posts: 220
Kudos: 1,195
How many numbers of this sequence of 342 numbers are odd? 10 Aug 2013, 13:02
Kudos
Add Kudos
Bookmarks
Bookmark this Post
blueseas
Asifpirlo
How many numbers of this sequence of 342 numbers are odd?
(1) The sequence starts with -1,3,-3,..........
(2) Except for the 1st two numbers, every number in the sequence is the product of the two immediately preceding numbers

Show Spoiler
publishing soon :-D

statement 1:The sequence starts with -1,3,-3,..........
insufficient as we dont know what all numbers are there in this series.

statement 2:Except for the 1st two numbers, every number in the sequence is the product of the two immediately preceding numbers
insufficient as we dont know what are numbers in the series.

combining:
first two numbers are -1,3...now the following numbers will be multiple of previous 2 numbers ...
you can see both numbers are ODD....and we know\(ODD*ODD = ODD\)..So clearly following digits will be ODD.
Hence we can conclude that all numbers are odd
hence sufficient.
C
Show more

yes thats it, perfect solution. All the 342 numbers are odd :-D
User avatar
vinnik
User avatar
Joined: 14 Dec 2011
Last visit: 02 May 2020
Posts: 54
Own Kudos:
189
Given Kudos: 86
Products:
My Reviews
Posts: 54
Kudos: 189
How many numbers of this sequence of 342 numbers are odd? 09 Sep 2013, 08:29
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Nice explanation.

I have a doubt in statement 1. Should a pattern be considered after reading the first 3 terms -1,3,-3,..........
I mean to say, i considered a pattern, a bit early i.e between -1 & 3 there is a gap of 4
between 3 & -3 there is a gap of 6
then between -3 & 1 there is a gap of 4 and then again 6 and so on.

-1,3,-3,1,-5.......

thus this gives odd numbers.
I am considering patterns early. Should there be more terms to confirm this pattern ? or is it a wrong pattern as nothing is defined.
I just want to clarify my doubt.

Looking forward for an explanation.

Thanks & Regards
Vinni
User avatar
Bunuel
User avatar
Math Expert
Joined: 02 Sep 2009
Last visit: 26 Apr 2026
Posts: 109,837
Own Kudos:
811,394
 [1]
Given Kudos: 105,896
Products:
GMAT Club Tests Forum Quiz
Expert
Expert reply
Active GMAT Club Expert! Tag them with @ followed by their username for a faster response.
Posts: 109,837
Kudos: 811,394
 [1]
How many numbers of this sequence of 342 numbers are odd? 10 Sep 2013, 03:10
1
Kudos
Add Kudos
Bookmarks
Bookmark this Post
vinnik
How many numbers of this sequence of 342 numbers are odd?
(1) The sequence starts with -1,3,-3,..........
(2) Except for the 1st two numbers, every number in the sequence is the product of the two immediately preceding numbers

Nice explanation.

I have a doubt in statement 1. Should a pattern be considered after reading the first 3 terms -1,3,-3,..........
I mean to say, i considered a pattern, a bit early i.e between -1 & 3 there is a gap of 4
between 3 & -3 there is a gap of 6
then between -3 & 1 there is a gap of 4 and then again 6 and so on.

-1,3,-3,1,-5.......

thus this gives odd numbers.
I am considering patterns early. Should there be more terms to confirm this pattern ? or is it a wrong pattern as nothing is defined.
I just want to clarify my doubt.

Looking forward for an explanation.

Thanks & Regards
Vinni
Show more

Yes, for (1) we cannot say what are the remaining terms in the sequence or what pattern if any is there.
avatar
unceldolan
avatar
Joined: 21 Oct 2013
Last visit: 03 Jun 2015
Posts: 151
Own Kudos:
247
Given Kudos: 19
Location: Germany
Schools: Owen '17 (A$) Sauder '17 (A$) Schulich '17 (WD) Anderson FEMBA '17 (S) McDonough '17 (A) Desautels '17 (S)
GMAT 1: 660 Q45 V36
GPA: 3.51
Schools: Owen '17 (A$) Sauder '17 (A$) Schulich '17 (WD) Anderson FEMBA '17 (S) McDonough '17 (A) Desautels '17 (S)
GMAT 1: 660 Q45 V36
Posts: 151
Kudos: 247
How many numbers of this sequence of 342 numbers are odd? 09 Jan 2014, 06:38
Kudos
Add Kudos
Bookmarks
Bookmark this Post
(1) Alone is clearly IS. You don't know what's coming next.
(2) Alone is IS, because you don't know anything about he numbers, which could be 2,4, 8 and so on.

(1) + (2) You can combine that ODD*ODD = ODD hence all numbers will be odd (since the sequence statrs with 3*-3). Thus C.
User avatar
bumpbot
User avatar
Non-Human User
Joined: 09 Sep 2013
Last visit: 04 Jan 2021
Posts: 38,988
Own Kudos:
1,118
Posts: 38,988
Kudos: 1,118
How many numbers of this sequence of 342 numbers are odd? 23 Jun 2020, 09:48
Kudos
Add Kudos
Bookmarks
Bookmark this Post
Automated notice from GMAT Club BumpBot:

A member just gave Kudos to this thread, showing it’s still useful. I’ve bumped it to the top so more people can benefit. Feel free to add your own questions or solutions.

This post was generated automatically.
Moderators:
Bunuel
Math Expert
109837 posts
kingbucky
498 posts
Gmat860sanskar
212 posts