Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 04 May 2015, 23:25

### 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

we will pick new questions that match your level based on your Timer History

Track

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

# Events & Promotions

###### Events & Promotions in June
Open Detailed Calendar

# Which of the following fractions has a decimal equivalent

Author Message
TAGS:
Intern
Joined: 11 Dec 2008
Posts: 24
Followers: 0

Kudos [?]: 0 [0], given: 0

Which of the following fractions has a decimal equivalent [#permalink]  03 Jan 2009, 11:58
Which of the following fractions has a decimal equivalent that is a terminating decimal?

A. 10/189
B. 15/196
C. 16/225
D. 25/144
E. 39/128

Need to know faster way to find the terminating decimal...thanks!
SVP
Joined: 29 Aug 2007
Posts: 2497
Followers: 57

Kudos [?]: 556 [0], given: 19

Re: Easier way to find a terminating decimal? [#permalink]  03 Jan 2009, 12:46
UnknownPhD wrote:
Which of the following fractions has a decimal equivalent that is a terminating decimal?

A. 10/189
B. 15/196
C. 16/225
D. 25/144
E. 39/128

Need to know faster way to find the terminating decimal...thanks!

look for denometer that has 2 and/or 5 as prime factor(s).

A. 10/189 = 2x5/(3x3x3x7) ------ 7?
B. 15/196 = 3x5/(2x2x2x2x3x3) ---- 3?
C. 16/225 = 2x2x2x2/(5x5x7) ---- 7?
D. 25/144 = 5x5/(2x2x2x2x3x3) ----3?
E. 39/128 = 3x13/(2x2x2x2x2x2x2) -----2. yes.

So E.
_________________
Manager
Joined: 15 Apr 2008
Posts: 166
Followers: 2

Kudos [?]: 10 [0], given: 1

Re: Easier way to find a terminating decimal? [#permalink]  03 Jan 2009, 13:17
GMAT TIGER wrote:
UnknownPhD wrote:
Which of the following fractions has a decimal equivalent that is a terminating decimal?

A. 10/189
B. 15/196
C. 16/225
D. 25/144
E. 39/128

Need to know faster way to find the terminating decimal...thanks!

look for denometer that has 2 and/or 5 as prime factor(s).

A. 10/189 = 2x5/(3x3x3x7) ------ 7?
B. 15/196 = 3x5/(2x2x2x2x3x3) ---- 3?
C. 16/225 = 2x2x2x2/(5x5x7) ---- 7?
D. 25/144 = 5x5/(2x2x2x2x3x3) ----3?
E. 39/128 = 3x13/(2x2x2x2x2x2x2) -----2. yes.

So E.

hi gmattiger
can you tell me how you decided on E as 2 is the factor in all the answers. also against each answer you have written a number towards the end. what does that mean?

VP
Joined: 30 Jun 2008
Posts: 1048
Followers: 11

Kudos [?]: 348 [2] , given: 1

Re: Easier way to find a terminating decimal? [#permalink]  04 Jan 2009, 06:50
2
KUDOS
UnknownPhD wrote:
Which of the following fractions has a decimal equivalent that is a terminating decimal?

A. 10/189
B. 15/196
C. 16/225
D. 25/144
E. 39/128

Need to know faster way to find the terminating decimal...thanks!

First, terminating decimals have a fixed number of digits after the decimal point.

For eg. 5/2 = 2.5 (this is a terminating decimal)
1/3 = 1.33333333 ( this is recurring decimal)

For a fraction to have terminating decimals, it can have only 2 and/or 5 as prime factors in the denominator ....

If we see all the denominators, we have prime factors other than 2 and 5. Only choice E has only prime factor as 2

A. 10/189 = 2x5/(3x3x3x7) ..... This has 3 and 7. So this will definitely have recurring decimals.
B. 15/196 = 3x5/(2x2x2x2x3x3) ..... This has 2 but this also has 3 which means this will definitely have recurring decimals.
C. 16/225 = 2x2x2x2/(5x5x7) ..... This has 5 but this also has 7 which means this will definitely have recurring decimals.
D. 25/144 = 5x5/(2x2x2x2x3x3) ..... This has 2 but this also has 3 which means this will definitely have recurring decimals.
E. 39/128 = 3x13/(2x2x2x2x2x2x2) -----2. This has ONLY 2. So this HAS to be a terminating decimal

Choice E has to be the right answer.

Hope this helped. If not, let me know.
_________________

"You have to find it. No one else can find it for you." - Bjorn Borg

Manager
Joined: 15 Apr 2008
Posts: 166
Followers: 2

Kudos [?]: 10 [0], given: 1

Re: Easier way to find a terminating decimal? [#permalink]  04 Jan 2009, 07:51
amitdgr wrote:
UnknownPhD wrote:
Which of the following fractions has a decimal equivalent that is a terminating decimal?

A. 10/189
B. 15/196
C. 16/225
D. 25/144
E. 39/128

Need to know faster way to find the terminating decimal...thanks!

First, terminating decimals have a fixed number of digits after the decimal point.

For eg. 5/2 = 2.5 (this is a terminating decimal)
1/3 = 1.33333333 ( this is recurring decimal)

For a fraction to have terminating decimals, it can have only 2 and/or 5 as prime factors in the denominator ....

If we see all the denominators, we have prime factors other than 2 and 5. Only choice E has only prime factor as 2

A. 10/189 = 2x5/(3x3x3x7) ..... This has 3 and 7. So this will definitely have recurring decimals.
B. 15/196 = 3x5/(2x2x2x2x3x3) ..... This has 2 but this also has 3 which means this will definitely have recurring decimals.
C. 16/225 = 2x2x2x2/(5x5x7) ..... This has 5 but this also has 7 which means this will definitely have recurring decimals.
D. 25/144 = 5x5/(2x2x2x2x3x3) ..... This has 2 but this also has 3 which means this will definitely have recurring decimals.
E. 39/128 = 3x13/(2x2x2x2x2x2x2) -----2. This has ONLY 2. So this HAS to be a terminating decimal

Choice E has to be the right answer.

Hope this helped. If not, let me know.

Thanks a lot. this is a good tip.
SVP
Joined: 29 Aug 2007
Posts: 2497
Followers: 57

Kudos [?]: 556 [1] , given: 19

Re: Easier way to find a terminating decimal? [#permalink]  04 Jan 2009, 10:38
1
KUDOS
ALD wrote:
GMAT TIGER wrote:
UnknownPhD wrote:
Which of the following fractions has a decimal equivalent that is a terminating decimal?

A. 10/189
B. 15/196
C. 16/225
D. 25/144
E. 39/128

Need to know faster way to find the terminating decimal...thanks!

look for denometer that has 2 and/or 5 as prime factor(s).

A. 10/189 = 2x5/(3x3x3x7) ------ 7?
B. 15/196 = 3x5/(2x2x2x2x3x3) ---- 3?
C. 16/225 = 2x2x2x2/(5x5x7) ---- 7?
D. 25/144 = 5x5/(2x2x2x2x3x3) ----3?
E. 39/128 = 3x13/(2x2x2x2x2x2x2) -----2. yes.

So E.

hi gmattiger
can you tell me how you decided on E as 2 is the factor in all the answers. also against each answer you have written a number towards the end. what does that mean?

The difference between E and any other answer choice is that E has only 2 where as others have 2 or 3 or 7. If the denomenator has 2 or 5 or both, the the fraction is terminating decimal.
_________________
Intern
Joined: 31 Dec 2008
Posts: 11
Followers: 0

Kudos [?]: 0 [0], given: 0

Re: Easier way to find a terminating decimal? [#permalink]  04 Jan 2009, 16:56
GMAT TIGER wrote:
Which of the following fractions has a decimal equivalent that is a terminating decimal?

A. 10/189
B. 15/196
C. 16/225
D. 25/144
E. 39/128

Need to know faster way to find the terminating decimal...thanks!

look for denometer that has 2 and/or 5 as prime factor(s).

A. 10/189 = 2x5/(3x3x3x7) ------ 7?
B. 15/196 = 3x5/(2x2x2x2x3x3) ---- 3?
C. 16/225 = 2x2x2x2/(5x5x7) ---- 7?
D. 25/144 = 5x5/(2x2x2x2x3x3) ----3?
E. 39/128 = 3x13/(2x2x2x2x2x2x2) -----2. yes.

So E.

hi gmattiger
can you tell me how you decided on E as 2 is the factor in all the answers. also against each answer you have written a number towards the end. what does that mean?

The difference between E and any other answer choice is that E has only 2 where as others have 2 or 3 or 7. If the denomenator has 2 or 5 or both, the the fraction is terminating decimal.

Good trick GMATTiger... until now I use to just calculate it manually... but I am smelling something wrong in this. I guess this needs to be improved a bit. For Ex take the case - 9/18,

here 18 = 2x3X3 but its terminating...

I guess improvement could be on the line that numerator has 2 or not, numerator and denominator are even/odd .. right now I am not able to frame it exactly .. but ya I can solve these questions with your trick now .. Thanks
GMAT Instructor
Joined: 24 Jun 2008
Posts: 978
Location: Toronto
Followers: 281

Kudos [?]: 799 [0], given: 3

Re: Easier way to find a terminating decimal? [#permalink]  04 Jan 2009, 18:30
mar2hathoda wrote:
GMAT TIGER wrote:
Which of the following fractions has a decimal equivalent that is a terminating decimal?

A. 10/189
B. 15/196
C. 16/225
D. 25/144
E. 39/128

Need to know faster way to find the terminating decimal...thanks!

look for denometer that has 2 and/or 5 as prime factor(s).

A. 10/189 = 2x5/(3x3x3x7) ------ 7?
B. 15/196 = 3x5/(2x2x2x2x3x3) ---- 3?
C. 16/225 = 2x2x2x2/(5x5x7) ---- 7?
D. 25/144 = 5x5/(2x2x2x2x3x3) ----3?
E. 39/128 = 3x13/(2x2x2x2x2x2x2) -----2. yes.

So E.

hi gmattiger
can you tell me how you decided on E as 2 is the factor in all the answers. also against each answer you have written a number towards the end. what does that mean?

The difference between E and any other answer choice is that E has only 2 where as others have 2 or 3 or 7. If the denomenator has 2 or 5 or both, the the fraction is terminating decimal.

Good trick GMATTiger... until now I use to just calculate it manually... but I am smelling something wrong in this. I guess this needs to be improved a bit. For Ex take the case - 9/18,

here 18 = 2x3X3 but its terminating...

I guess improvement could be on the line that numerator has 2 or not, numerator and denominator are even/odd .. right now I am not able to frame it exactly .. but ya I can solve these questions with your trick now .. Thanks

You need to reduce your fractions first. I explained all of this in detail on another forum:

www.beatthegmat.com/terminating-decimal-t11910.html
_________________

Nov 2011: After years of development, I am now making my advanced Quant books and high-level problem sets available for sale. Contact me at ianstewartgmat at gmail.com for details.

Private GMAT Tutor based in Toronto

SVP
Joined: 29 Aug 2007
Posts: 2497
Followers: 57

Kudos [?]: 556 [0], given: 19

Re: Easier way to find a terminating decimal? [#permalink]  04 Jan 2009, 21:28
mar2hathoda wrote:
Good trick GMATTiger... until now I use to just calculate it manually... but I am smelling something wrong in this. I guess this needs to be improved a bit. For Ex take the case - 9/18,

here 18 = 2x3X3 but its terminating...

I guess improvement could be on the line that numerator has 2 or not, numerator and denominator are even/odd .. right now I am not able to frame it exactly .. but ya I can solve these questions with your trick now .. Thanks

9/18 cannot be an option. It is in fact 1/2, which has 2 in denominator..
_________________
Re: Easier way to find a terminating decimal?   [#permalink] 04 Jan 2009, 21:28
Similar topics Replies Last post
Similar
Topics:
Which of the following fractions has a decimal equivalent 2 09 Dec 2007, 16:43
3 Which of the following fractions has a decimal equivalent 14 02 Apr 2007, 05:18
Which of the following fractions has a decimal equivalent 14 08 Oct 2006, 09:12
Which of the following fractions has a decimal equivalent 3 21 Jul 2006, 19:56
Which of the following fractions has a decimal equivalent 2 16 Jan 2006, 10:21
Display posts from previous: Sort by

# Which of the following fractions has a decimal equivalent

 Powered by phpBB © phpBB Group and phpBB SEO Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.