A sequence 1, 2, 3, 4. What is the tens' digit of the sum of : Quant Question Archive [LOCKED]
Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack

 It is currently 24 Jan 2017, 02:28

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

A sequence 1, 2, 3, 4. What is the tens' digit of the sum of

Author Message
Senior Manager
Joined: 08 Aug 2005
Posts: 251
Followers: 1

Kudos [?]: 49 [0], given: 0

A sequence 1, 2, 3, 4. What is the tens' digit of the sum of [#permalink]

Show Tags

09 Aug 2006, 00:47
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

A sequence 1, 2, 3, 4. What is the tens' digit of the sum of first forty terms?
Senior Manager
Joined: 19 Jul 2006
Posts: 361
Followers: 2

Kudos [?]: 6 [0], given: 0

Show Tags

09 Aug 2006, 04:17
sum = n(n+1)/2 = 40*41/2 = 820
Senior Manager
Joined: 14 Jul 2005
Posts: 402
Followers: 1

Kudos [?]: 27 [0], given: 0

Show Tags

13 Aug 2006, 10:49
agree with AK 2 it is !
Manager
Joined: 20 Mar 2006
Posts: 200
Followers: 1

Kudos [?]: 3 [0], given: 0

Show Tags

13 Aug 2006, 16:22
getzgetzu wrote:
A sequence 1, 2, 3, 4. What is the tens' digit of the sum of first forty terms?

is the Q 1+2+3+4...+38+39+40 ??

Arithmetic progression = 20[2+39]
= 20*41
= 820

Hence tens digit =2

Heman
Senior Manager
Joined: 21 Jun 2006
Posts: 285
Followers: 1

Kudos [?]: 113 [0], given: 0

Show Tags

13 Aug 2006, 17:01
for n consecutive integers,
sum is n(n+1)/2
for 40 integers consecutive - 40*41/2=820

Tens digit 2
Intern
Joined: 08 May 2006
Posts: 19
Followers: 0

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

Show Tags

15 Aug 2006, 02:58
the ten digit is 2.

Sum of first n number is n( n+1) /2 = 40 ( 41) /2 = 820

tenth Digit is 2
15 Aug 2006, 02:58
Display posts from previous: Sort by

A sequence 1, 2, 3, 4. What is the tens' digit of the sum of

 Powered by phpBB © phpBB Group and phpBB SEO Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.