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 350,000 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: If d=1/(2^3*5^7) is expressed as a terminating decimal, how [#permalink]
20 Dec 2012, 05:12

15

This post received KUDOS

Expert's post

14

This post was BOOKMARKED

Walkabout wrote:

If d=1/(2^3*5^7) is expressed as a terminating decimal, how many nonzero digits will d have?

(A) One (B) Two (C) Three (D) Seven (E) Ten

Given: \(d=\frac{1}{2^3*5^7}\).

Multiply by \(\frac{2^4}{2^4}\) --> \(d=\frac{2^4}{(2^3*5^7)*2^4}=\frac{2^4}{2^7*5^7}=\frac{2^4}{10^7}=\frac{16}{10^7}=0.0000016\). Hence \(d\) will have two non-zero digits, 16, when expressed as a decimal.

Re: If d=1/(2^3*5^7) is expressed as a terminating decimal, how [#permalink]
17 Aug 2013, 18:02

Bunuel wrote:

Bumping for review and further discussion.

Bunuel I actually, do have question.

The expression is equal to 1/(2*5)^3(5^4)=1/625,000. Knowing this expression alone. Is there a way to figure out the answer? Just didn't occur to me to multiply by 2^4

Re: If d=1/(2^3*5^7) is expressed as a terminating decimal, how [#permalink]
21 Oct 2013, 00:59

Bunuel wrote:

Walkabout wrote:

If d=1/(2^3*5^7) is expressed as a terminating decimal, how many nonzero digits will d have?

(A) One (B) Two (C) Three (D) Seven (E) Ten

Given: \(d=\frac{1}{2^3*5^7}\).

Multiply by \(\frac{2^4}{2^4}\) --> \(d=\frac{2^4}{(2^3*5^7)*2^4}=\frac{2^4}{2^7*5^7}=\frac{2^4}{10^7}=\frac{16}{10^7}=0.0000016\). Hence \(d\) will have two non-zero digits, 16, when expressed as a decimal.

Answer: B.

Is there any other method to do it . I mean it is difficult to think of 2^4 there and then .

Re: If d=1/(2^3*5^7) is expressed as a terminating decimal, how [#permalink]
29 Dec 2013, 11:57

Bunuel wrote:

Walkabout wrote:

If d=1/(2^3*5^7) is expressed as a terminating decimal, how many nonzero digits will d have?

(A) One (B) Two (C) Three (D) Seven (E) Ten

Given: \(d=\frac{1}{2^3*5^7}\).

Multiply by \(\frac{2^4}{2^4}\) --> \(d=\frac{2^4}{(2^3*5^7)*2^4}=\frac{2^4}{2^7*5^7}=\frac{2^4}{10^7}=\frac{16}{10^7}=0.0000016\). Hence \(d\) will have two non-zero digits, 16, when expressed as a decimal.

Answer: B.

I have seen couple of more problem like this. One thing is still not clear to me. When you multiply whole denominator by 2^4 why is 5^7 getting ignored? Shouldn't 2^4 multiply both 2^3 as well as 5^7?

Re: If d=1/(2^3*5^7) is expressed as a terminating decimal, how [#permalink]
29 Dec 2013, 12:00

1

This post received KUDOS

Expert's post

theGame001 wrote:

Bunuel wrote:

Walkabout wrote:

If d=1/(2^3*5^7) is expressed as a terminating decimal, how many nonzero digits will d have?

(A) One (B) Two (C) Three (D) Seven (E) Ten

Given: \(d=\frac{1}{2^3*5^7}\).

Multiply by \(\frac{2^4}{2^4}\) --> \(d=\frac{2^4}{(2^3*5^7)*2^4}=\frac{2^4}{2^7*5^7}=\frac{2^4}{10^7}=\frac{16}{10^7}=0.0000016\). Hence \(d\) will have two non-zero digits, 16, when expressed as a decimal.

Answer: B.

I have seen couple of more problem like this. One thing is still not clear to me. When you multiply whole denominator by 2^4 why is 5^7 getting ignored? Shouldn't 2^4 multiply both 2^3 as well as 5^7?

Thanks

Frankly, the red part does not make any sense...

The denominator is \(2^7*5^7\). Multiply it by \(2^4\). What do you get? _________________

Re: If d=1/(2^3*5^7) is expressed as a terminating decimal, how [#permalink]
11 Mar 2014, 15:54

Bunuel wrote:

Walkabout wrote:

If d=1/(2^3*5^7) is expressed as a terminating decimal, how many nonzero digits will d have?

(A) One (B) Two (C) Three (D) Seven (E) Ten

Given: \(d=\frac{1}{2^3*5^7}\).

Multiply by \(\frac{2^4}{2^4}\) --> \(d=\frac{2^4}{(2^3*5^7)*2^4}=\frac{2^4}{2^7*5^7}=\frac{2^4}{10^7}=\frac{16}{10^7}=0.0000016\). Hence \(d\) will have two non-zero digits, 16, when expressed as a decimal.

Answer: B.

What is it that you saw that indicated you should multiply by 2^4. Just looking at the problem that never occurred to me and I'd like to understand why it did to you.

Re: If d=1/(2^3*5^7) is expressed as a terminating decimal, how [#permalink]
11 Mar 2014, 22:36

1

This post received KUDOS

Expert's post

WinterIsComing wrote:

Bunuel wrote:

Walkabout wrote:

If d=1/(2^3*5^7) is expressed as a terminating decimal, how many nonzero digits will d have?

(A) One (B) Two (C) Three (D) Seven (E) Ten

Given: \(d=\frac{1}{2^3*5^7}\).

Multiply by \(\frac{2^4}{2^4}\) --> \(d=\frac{2^4}{(2^3*5^7)*2^4}=\frac{2^4}{2^7*5^7}=\frac{2^4}{10^7}=\frac{16}{10^7}=0.0000016\). Hence \(d\) will have two non-zero digits, 16, when expressed as a decimal.

Answer: B.

What is it that you saw that indicated you should multiply by 2^4. Just looking at the problem that never occurred to me and I'd like to understand why it did to you.

We need to multiply by 2^6/2^6 in order to convert the denominator to the base of 10 and then to convert the fraction into the decimal form: 0.xxxx.

Re: If d=1/(2^3*5^7) is expressed as a terminating decimal, how [#permalink]
05 Jun 2015, 12:14

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email. _________________