Forum Home > GMAT > Quantitative > Problem Solving (PS)
Events & Promotions
|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
Dec 1511:00 AM IST
-01:00 PM IST
Attend this free GMAT Algebra Webinar and learn how to master the most challenging Inequalities and Absolute Value problems with ease.
Dec 1410:00 AM EST
-12:00 PM EST
Think a 100% GMAT Verbal score is out of your reach? Target Test Prep will make you think again! Our course uses techniques such as topical study and spaced repetition to maximize knowledge retention and make studying simple and fun.- Dec 14
11:00 AM IST
-01:00 PM IST
Attend this session to learn how to Deconstruct arguments, Pre-Think Author’s Assumptions, and apply Negation Test. 
Dec 1608:00 AM PST
-11:59 PM PST
GMAT Club 12 Days of Christmas is a 4th Annual GMAT Club Winter Competition based on solving questions. This is the Winter GMAT competition on GMAT Club with an amazing opportunity to win over $40,000 worth of prizes!- Dec 17
09:00 AM PST
-10:00 AM PST
Join Manhattan Prep instructor Whitney Garner for a fun—and thorough—review of logic-based (non-math) problems, with a particular emphasis on Data Sufficiency and Two-Parts. - Dec 18
10:00 AM PST
-11:00 AM PST
Here is the essential guide to securing scholarships as an MBA student! In this video, we explore the various types of scholarships available, including need-based and merit-based options.
07 Jul 2022, 01:30
Kudos
Bookmarks
D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
25%
(medium)
Question Stats:
77% (01:49) correct
23%
(02:17)
wrong
based on 52
sessions
History
Date
Time
Result
Not Attempted Yet
A is the product of the first 100 multiples of 8. How many zeros would be there at the end of A?
(A) 10
(B) 11
(C) 12
(D) 24
(E) 25
Are You Up For the Challenge: 700 Level Questions
(A) 10
(B) 11
(C) 12
(D) 24
(E) 25
Are You Up For the Challenge: 700 Level Questions
07 Jul 2022, 02:28
Kudos
Bookmarks
A laborious process, which is also error-prone, is to list all the multiples of 8 that ends with 0 (or 00).
Alternatively, realizing that we have an oversupply of 2's, we just need to figure out how many 5's are there in the product of the first 100 multiples of 8.
8 does not contribute any 5's. We need to count the number of 5's in 1*2*3*...*100
A systematic way to do so is
Firstly, 100/5 = 20
Secondly, 100/25 = 4
(And 25*5 is already larger than 100)
So the number of 5's is 20+4 = 24.
The answer is (D).
Alternatively, realizing that we have an oversupply of 2's, we just need to figure out how many 5's are there in the product of the first 100 multiples of 8.
8 does not contribute any 5's. We need to count the number of 5's in 1*2*3*...*100
A systematic way to do so is
Firstly, 100/5 = 20
Secondly, 100/25 = 4
(And 25*5 is already larger than 100)
So the number of 5's is 20+4 = 24.
The answer is (D).
07 Jul 2022, 03:27
Kudos
Bookmarks
A = 8 x 16 x 24 ...... x 800
To find the number of trailing 0(s), we need combination of 2 and 5 and since 8 already has 2 as a factor, we need to count the number of 5(s) in first 100 multiples of 8 to get the number of trailing 0(s)
We will get 5 in each 5th multiple of 8 (40,80,120...) and hence a 0 will be added at the end at each 5th multiple of 8 since its a product
So in this way we get 100/5 = 20 zeros
But, 25th (5x5), 50th (5x5x2), 75th (5x5x3) and 100th (5x5x4) multiples of 8 have 2 fives so an extra zero needs to be added to our tally so another 4
Total zeros = 24
Answer - D
Posted from my mobile device
To find the number of trailing 0(s), we need combination of 2 and 5 and since 8 already has 2 as a factor, we need to count the number of 5(s) in first 100 multiples of 8 to get the number of trailing 0(s)
We will get 5 in each 5th multiple of 8 (40,80,120...) and hence a 0 will be added at the end at each 5th multiple of 8 since its a product
So in this way we get 100/5 = 20 zeros
But, 25th (5x5), 50th (5x5x2), 75th (5x5x3) and 100th (5x5x4) multiples of 8 have 2 fives so an extra zero needs to be added to our tally so another 4
Total zeros = 24
Answer - D
Posted from my mobile device
