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

It is currently 29 Aug 2015, 19:54
GMAT Club Tests

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.

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

How many number of times will the digit

  Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
Intern
Intern
avatar
Joined: 10 Oct 2003
Posts: 45
Location: Finland
Followers: 1

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

How many number of times will the digit [#permalink] New post 30 Oct 2003, 05:33
00:00
A
B
C
D
E

Difficulty:

(N/A)

Question Stats:

0% (00:00) correct 0% (00:00) wrong based on 0 sessions
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

How many number of times will the digit тАШ7' be written when listing the integers from 1 to 1000?


(1) 271 (2) 300 (3) 252 (4) 304 (5) 312
Manager
Manager
avatar
Joined: 26 Aug 2003
Posts: 233
Location: United States
Followers: 1

Kudos [?]: 2 [0], given: 0

 [#permalink] New post 30 Oct 2003, 06:09
300 times just like any other integer but 0. I'd say 1 also but 1 is dependent on whether the boundaries are inclusive.
SVP
SVP
User avatar
Joined: 03 Feb 2003
Posts: 1607
Followers: 6

Kudos [?]: 107 [0], given: 0

 [#permalink] New post 30 Oct 2003, 06:14
one-position numbers: one 7 = 1
two-position numbers: X7 (eight), 7X (nine), and 77 (two) = 19
three-position numbers: XX7 (8*9), X7X (8*9), 7XX (9*9), 77X (nine*2), 7X7 (nine*2), X77 (eight*2), 777 (three)

1+19+72+72+81+18+18+16+3=300

oops :oops: :oops:

any other approaches?
Manager
Manager
avatar
Joined: 26 Aug 2003
Posts: 233
Location: United States
Followers: 1

Kudos [?]: 2 [0], given: 0

 [#permalink] New post 30 Oct 2003, 07:18
stolyar wrote:
one-position numbers: one 7 = 1
two-position numbers: X7 (eight), 7X (nine), and 77 (two) = 19
three-position numbers: XX7 (8*9), X7X (8*9), 7XX (9*9), 77X (nine*2), 7X7 (nine*2), X77 (eight*2), 777 (three)

1+19+72+72+81+18+18+16+3=300

oops :oops: :oops:

any other approaches?

stolyar,

I derived this formula (out of my habit) after some calculations and testing that seems to work well so far.

For this example:
n = # of zero's the higher range ...... (3 in this case)
S = # of times a digit occurs ...... (# of times 7 occurs)

S = n * 10^(n - 1)
= 3 * 10^2
= 300

Let me know if anyone wants the theoretical proof for my formula.
  [#permalink] 30 Oct 2003, 07:18
Display posts from previous: Sort by

How many number of times will the digit

  Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Privacy Policy| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

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®.