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.

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:

So as far as I understood, any fraction that has a denom., which has 2 and 5 as the only prime factors, is a terminating decimal?
Is it a sufficient condition always?

So as far as I understood, any fraction that has a denom., which has 2 and 5 as the only prime factors, is a terminating decimal? Is it a sufficient condition always?

The key point to be noted here is :
Terminating decimal --> A number having a 'fixed' number of decimal places...==> Can be expressed as N/(10^n).....

=> Deno ..i.e 10 ^n= 2^n . 5^n.....

Then it means Yes...sufficient enough...
(Note the 5^n has disappaered when converting to N/10^n form a term will appear in num which will cancel out 5^n factor)

PS: BTW do a search in the forum ...this problem has been covered lot many times here...

Last edited by suithink on 02 Apr 2007, 09:41, edited 1 time in total.

The fraction will terminate if and only if the denominator has for
prime divisors only 2 and 5, that is, if and only if the denominator
has the form 2^a * 5^b for some exponents a >= 0 and b >= 0. The
number of decimal places until it terminates is the larger of a and b.

i sort of figured this out on my own by testing... oh... i don't know about 10 or 20 numbers during a practice CAT ) definately a huge time waster. it is nice to know the actual reasoning behind it and that it works all the time without question.

i recognized that anytime when a denominator has factors of 2 AND 5 to some power (5^0 or 2^0 still count) it is terminiating. of course any number in the denominator with other factors can lead to a terminiating decimal depending on the numerator (3/30 etc...) but i don't think that when we see a question like this they are looking to test us on that...

Re: Which of the following fractions has a decimal equivalent [#permalink]
18 Nov 2011, 06:18

1

This post received KUDOS

The lesson I learned today:

Be careful about nominators as well. Because sometimes test makers provide a nominator that can simplify the factors of denominator. For example \frac{18}{225}

At first glance, 3 is a factor of denominator, so we conclude that this fraction is not terminating. but nominator is 18! So the simplified fraction is \frac{2}{25} and terminating.

gmatclubot

Re: Which of the following fractions has a decimal equivalent
[#permalink]
18 Nov 2011, 06:18

I couldn’t help myself but stay impressed. young leader who can now basically speak Chinese and handle things alone (I’m Korean Canadian by the way, so...