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.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

Now, \(10^6-1\) is very close to \(10^6\) and \(10^4-1\) is very close to \(10^4\), hence \(\frac{10^6-1}{10*(10^4-1)}\approx{\frac{10^6}{10*10^4}=\frac{10^6}{10^5}=10}\).

Answer: B.

Or else you can notice that we need approximate value of a fraction. Now, \(10^{8}\) is much, much, much bigger than \(10^{2}\). So subtracting \(10^{2}\) from \(10^{8}\) will be very close to \(10^{8}\), basically \(10^{2}\) is negligible in this case. The same for for \(10^{7}\) and \(10^{3}\). So \(\frac{10^8-10^2}{10^7-10^3}\approx{\frac{10^8}{10^7}=10\).

Re: The value of (10^8-10^2)/(10^7-10^3) is closest to which of [#permalink]

Show Tags

25 Jun 2010, 22:59

3

This post received KUDOS

1

This post was BOOKMARKED

Because the question asks for what value is "closest" the question invites approximation.

Let's look at the numerator:

10^8 - 10^2

10^8 is HUGE compared to 10^2.

So 10^8 - 10^2 is very close to 10^8 itself. (Just as 100 - 0.0001 is very close to 100 itself).

Likewise, 10^7 is HUGE compared to 10^3.

So 10^7 - 10^3 is very close to 10^7.

So we have:

10^8/10^7

or 10^(8-7) = 10.

Choose B.

___

I think this is the quickest way to solve. If you see the point of the question, you can quickly solve it in this way without even having to do any scratchwork.

TAKEAWAY: don't assume algebraic approaches are always most efficient. And whenever a question asks for "approximation" or "close" be on the lookout to make deductions that will allow you to solve the question fast.

Re: The value of (10^8-10^2)/(10^7-10^3) is closest to which of [#permalink]

Show Tags

18 Sep 2010, 14:03

2

This post received KUDOS

ok. without calculation you can probably guess 10^8 and 10^7 are SIGNIFICANTLY bigger than the numbers they are subtracting. so you can just do 10^8 / 10^7 = 10. B
_________________

Re: The value of (10^8-10^2)/(10^7-10^3) is closest to which of [#permalink]

Show Tags

18 Sep 2010, 15:28

shaselai wrote:

ok. without calculation you can probably guess 10^8 and 10^7 are SIGNIFICANTLY bigger than the numbers they are subtracting. so you can just do 10^8 / 10^7 = 10. B

Good quick thinking on your part . I took the more traditional approach of solving it the long way
_________________

Support GMAT Club by putting a GMAT Club badge on your blog

This gives 10. The great part is that you are dealing with such large numbers, that 1 and 10 are immaterial.

The point here is not accuracy, it is to get a sense of what is right or wrong. If you find you have to do long division, then you are definitely missing a trick. Even if a question seems fiendish, there is always a shortcut to the solution!

Hope this helps.

EDIT: Scrolled through Bunuel's post, who has hit the nail on the head

Re: The value of (10^8-10^2)/(10^7-10^3) is closest to which of [#permalink]

Show Tags

02 Jul 2013, 02:01

1

This post received KUDOS

jcbruin wrote:

The value of (10^8-10^2)/(10^7-10^3) is closest to which of the following?

A. 1 B. 10 C. 10^2 D. 10^3 E. 10^4

The given expression can be written as : \(\frac {10^8(1-\frac{10^2}{10^8})} {10^7(1-\frac{10^3}{10^7})}\) = \(\frac {10^8(1-\frac{1}{10^6})} {10^7(1-\frac{1}{10^4})}\)

We know that \(\frac {1} {10^6}\ll1\) and similarly,\(\frac {1} {10^4}\ll1\), thus, we can safely approximate the given expression as\(\frac {10^8}{10^7}\) =10. B.
_________________

Its been long time coming. I have always been passionate about poetry. It’s my way of expressing my feelings and emotions. And i feel a person can convey...

Written by Scottish historian Niall Ferguson , the book is subtitled “A Financial History of the World”. There is also a long documentary of the same name that the...

Post-MBA I became very intrigued by how senior leaders navigated their career progression. It was also at this time that I realized I learned nothing about this during my...