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:

Re: repeating decimals [#permalink]
11 Feb 2009, 00:00

You can solve this pretty quickly using approximation.

A) 2/11 can be approx. to 2/10 = 1/5 = 0.2 B) 1/3 = 0.33 C) 41/99 can be approx. to 40/100 = 2/5 = 0.4 D) 2/3 = 0.66 E) 23/37... mmh, the weird one; if you want to double check you can proceed with the division (which yields 0.621, hence the longest sequence of different digits).

Re: repeating decimals [#permalink]
11 Feb 2009, 02:51

2

This post received KUDOS

Expert's post

There is a general rule: 0.(abcd)=abcd/9999. So, the more "9" we need to write out our fraction in such way, the longer sequence we have. (You can use search to find my prove of this rule). Moreover, if we have proper fraction x/y, x doesn't influence on length of a sequence.

1) First of all, let's take a fast look at our options. Are their proper fraction? Or do we need to change them? All fractions are proper fractions.

2) cut numerators.

3) Can we compose 9 out of each denominators? Only for B and D. They are out.

4) Can we compose 99 out of each denominators? Only for A and C. They are out. Only E remains. In other words, 1/37 (23/37) has sequence consisted of more than two digits.

If you've truly grasped this way, you can solve problems like that under 20 sec and without complex calculations. _________________

Re: repeating decimals [#permalink]
11 Feb 2009, 07:10

walker wrote:

There is a general rule: 0.(abcd)=abcd/9999. So, the more "9" we need to write out our fraction in such way, the longer sequence we have. (You can use search to find my prove of this rule). Moreover, if we have proper fraction x/y, x doesn't influence on length of a sequence.

1) First of all, let's take a fast look at our options. Are their proper fraction? Or do we need to change them? All fractions are proper fractions.

2) cut numerators.

3) Can we compose 9 out of each denominators? Only for B and D. They are out.

4) Can we compose 99 out of each denominators? Only for A and C. They are out. Only E remains. In other words, 1/37 (23/37) has sequence consisted of more than two digits.

If you've truly grasped this way, you can solve problems like than under 20 sec and without complex calculations.

Walker = Genius

+1

Thanks buddy for a great tip. _________________

Your attitude determines your altitude Smiling wins more friends than frowning

Re: repeating decimals [#permalink]
11 Feb 2009, 07:41

3

This post received KUDOS

Expert's post

There is a prove. It is better to remember a formula when it is understandable

\(1/a=0.(b)=b*(10^{-n}+10^{-2n}+10^{-3n.....}+...)=b*\frac{10^{-n}}{1-10^{-n}}=b*\frac{1}{10^{n}-1}=\frac{b}{99...99_n}\) where n - the length of sequence (the number of digits of b) _________________

Re: repeating decimals [#permalink]
11 Feb 2009, 09:01

walker, how can u b soooooo perfect in maths?Give us also sum tips. U r simply marvellous! needless 2 say +1 frm me

walker wrote:

There is a general rule: 0.(abcd)=abcd/9999. So, the more "9" we need to write out our fraction in such way, the longer sequence we have. (You can use search to find my prove of this rule). Moreover, if we have proper fraction x/y, x doesn't influence on length of a sequence.

1) First of all, let's take a fast look at our options. Are their proper fraction? Or do we need to change them? All fractions are proper fractions.

2) cut numerators.

3) Can we compose 9 out of each denominators? Only for B and D. They are out.

4) Can we compose 99 out of each denominators? Only for A and C. They are out. Only E remains. In other words, 1/37 (23/37) has sequence consisted of more than two digits.

If you've truly grasped this way, you can solve problems like than under 20 sec and without complex calculations.

Re: repeating decimals [#permalink]
11 Feb 2009, 10:10

walker wrote:

There is a general rule: 0.(abcd)=abcd/9999. So, the more "9" we need to write out our fraction in such way, the longer sequence we have. (You can use search to find my prove of this rule). Moreover, if we have proper fraction x/y, x doesn't influence on length of a sequence.

1) First of all, let's take a fast look at our options. Are their proper fraction? Or do we need to change them? All fractions are proper fractions.

2) cut numerators.

3) Can we compose 9 out of each denominators? Only for B and D. They are out.

4) Can we compose 99 out of each denominators? Only for A and C. They are out. Only E remains. In other words, 1/37 (23/37) has sequence consisted of more than two digits.

If you've truly grasped this way, you can solve problems like than under 20 sec and without complex calculations.

wow this is EXACTLY what I was looking for..gmatclub is blessed to have you math gurus here...thanks alot!

Re: repeating decimals [#permalink]
11 Feb 2009, 10:59

walker wrote:

There is a general rule: 0.(abcd)=abcd/9999. So, the more "9" we need to write out our fraction in such way, the longer sequence we have. (You can use search to find my prove of this rule). Moreover, if we have proper fraction x/y, x doesn't influence on length of a sequence.

1) First of all, let's take a fast look at our options. Are their proper fraction? Or do we need to change them? All fractions are proper fractions.

2) cut numerators.

3) Can we compose 9 out of each denominators? Only for B and D. They are out.

4) Can we compose 99 out of each denominators? Only for A and C. They are out. Only E remains. In other words, 1/37 (23/37) has sequence consisted of more than two digits.

If you've truly grasped this way, you can solve problems like than under 20 sec and without complex calculations.

Words are less to appreciate this explanation. wonderful GMAT Tip. +1 from me too.