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# General question regarding parenthesis.

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Intern
Joined: 07 May 2015
Posts: 7
General question regarding parenthesis.  [#permalink]

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09 May 2015, 10:07
1
Hi there,

I have a question regarding the use of parenthesis and dividing/multiplication.

As an example:
$$(1,5 * 10^3) / (0,5 * 10^6) = (1,5 / 0,5) * (10^3 / 10^6)$$

Why can you just switch $$10^3$$ with $$0,5$$ and then switch the dividing and multiplication signs. I have no idea when to
use methods or apply rules like this so if anyone has an explanation
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Re: General question regarding parenthesis.  [#permalink]

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09 May 2015, 10:53
Hi MarcvR,

It sounds like you're interested in broader PEMDAS (Parentheses, Exponents, Multiplication, Division, Addition, Subtraction) rules. These rules dictate the order in which you have to do calculations.

In the prompt you've provided, no calculations have actually been done - the prompt has just been re-written (and it's worth noting that the 10^3 and 0.5 were NOT "switched").

Notice how the numbers in both the numerator and denominator are MULTIPLIED. This means that we can re-write the fraction in a variety of different ways. The example that you listed is complex-looking, so I'm going to show you some simpler examples:

(1/2)(3/5) can be rewritten in any of the following ways (notice that the end calculation is always the SAME):

(1/2)(3/5) = 3/10

(1x3)/(2x5) = 3/10

(3x1)/(5x2) = 3/10

(1/5)(3/2) = 3/10

The same rules apply to the example that you listed. It might be that you just need more practice with hands-on calculations.

How long have you been studying?
What resources have you been using?
What is your goal score?
When are you planning to take the GMAT?

GMAT assassins aren't born, they're made,
Rich
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Contact Rich at: Rich.C@empowergmat.com

# Rich Cohen

Co-Founder & GMAT Assassin

Special Offer: Save $75 + GMAT Club Tests Free Official GMAT Exam Packs + 70 Pt. Improvement Guarantee www.empowergmat.com/ ***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!*********************** GMAT Tutor Joined: 24 Jun 2008 Posts: 1345 Re: General question regarding parenthesis. [#permalink] ### Show Tags 09 May 2015, 10:54 1 Here, you're just using the rule for multiplying fractions, but in reverse. You have probably learned that: $$\left( \frac{a}{b} \right) \left( \frac{c}{d} \right) = \frac{ac}{bd}$$ This rule works in both directions; if we have something that looks like the left side, we can rewrite it to look like the right side, and vice versa. In your example, you start with something that looks like the right side of the equation above, and have rewritten it to look like the left side. _________________ GMAT Tutor in Toronto If you are looking for online GMAT math tutoring, or if you are interested in buying my advanced Quant books and problem sets, please contact me at ianstewartgmat at gmail.com Intern Joined: 07 May 2015 Posts: 7 Re: General question regarding parenthesis. [#permalink] ### Show Tags 10 May 2015, 06:03 Thanks for the great help both! Based on your information I can apply and understand the rules for this question. I have a lot of problems with recognizing a question and apply the right rule to it. But I believe that a lot of practice will get me to the right spot. EMPOWERgmatRichC How long have you been studying? I have been studying for like 2/3 months (with the last month hardcore) but I primarily focussed on verbal until now. What resources have you been using? The website gmatcursus.nl. It is a website where you have 15 chapters with video lessons for both Quantative and Verbal, a random test generator What is your goal score? My goal score is 680-700 When are you planning to take the GMAT? I want to take the test around the 3th of June so if I fail the first time I can retry it around 3 more times before school starts. EMPOWERgmat Instructor Status: GMAT Assassin/Co-Founder Affiliations: EMPOWERgmat Joined: 19 Dec 2014 Posts: 12189 Location: United States (CA) GMAT 1: 800 Q51 V49 GRE 1: Q170 V170 Re: General question regarding parenthesis. [#permalink] ### Show Tags 10 May 2015, 10:25 Hi MarcvR, Have you taken any FULL-LENGTH practice CATs yet? If so, then what were your scores (including the Quant and Verbal Scaled Scores)? Based on what you've described, you might not have given yourself enough time to score at the desired level by June 3rd. I would never have you 'rush in' to take the GMAT if you didn't feel ready. By your own admission, if you have the room in your calendar to take the GMAT multiple times, then you could push back this Test Date, study some more and save some money. GMAT assassins aren't born, they're made, Rich _________________ 760+: Learn What GMAT Assassins Do to Score at the Highest Levels Contact Rich at: Rich.C@empowergmat.com # Rich Cohen Co-Founder & GMAT Assassin Special Offer: Save$75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/

***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************

Intern
Joined: 07 May 2015
Posts: 7
Re: General question regarding parenthesis.  [#permalink]

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11 May 2015, 01:56
Hi Rich,

I took one CAT-test so far but it did not include the AWA section. I scored 540 on the first try with 4 out of 12 IR, 21 out of 37 Q and 25 out of 41 V. The scores: 3 IR, 33Q and 31V. I have no idea why I scored higher on quantative by the way..

Maybe you are right and I should push it back a week or two. First I am going to complete all my quantative lessons and read all about the AWA on this forum. Then I am going to take all the CAT-test (3) that I have left. Then I am going to take the first real G-mat where I hope to score atleast 600. If I still have a few weeks before school starts I will consider to study more and get a higher score.

But let's first try to get control of the quantative section!
EMPOWERgmat Instructor
Status: GMAT Assassin/Co-Founder
Affiliations: EMPOWERgmat
Joined: 19 Dec 2014
Posts: 12189
Location: United States (CA)
GMAT 1: 800 Q51 V49
GRE 1: Q170 V170
Re: General question regarding parenthesis.  [#permalink]

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11 May 2015, 11:38
Hi MarcvR,

When it comes to properly preparing to face the Official GMAT, there is NO substitute for taking FULL-LENGTH CATs in a realistic and test-like fashion. When you take your next CAT, you MUST take the FULL CAT in one sitting in a way that matches Test Day in as many details as you can reasonably control.

Endurance and fatigue issues are aspects of the the GMAT that some Test Takers do not properly prepare for. Then, on Test Day, they aren't ready to face those issues and get 'killed.' The GMAT is a remarkably consistent and predictable Exam, so you CAN make your practice match. By putting in the extra effort and training now, you'll find Test Day to be easier to deal with.

GMAT assassins aren't born, they're made,
Rich
_________________

760+: Learn What GMAT Assassins Do to Score at the Highest Levels
Contact Rich at: Rich.C@empowergmat.com

# Rich Cohen

Co-Founder & GMAT Assassin

Special Offer: Save $75 + GMAT Club Tests Free Official GMAT Exam Packs + 70 Pt. Improvement Guarantee www.empowergmat.com/ ***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!*********************** Intern Joined: 07 May 2015 Posts: 7 Re: General question regarding parenthesis. [#permalink] ### Show Tags 12 May 2015, 02:12 Hi Rich, Thanks again for the advice! The CAT-test that I have access to right now doesn't include the AWA. When I have the feeling I practiced enough, I will find and take a full CAT-test to see how I perform. EMPOWERgmat Instructor Status: GMAT Assassin/Co-Founder Affiliations: EMPOWERgmat Joined: 19 Dec 2014 Posts: 12189 Location: United States (CA) GMAT 1: 800 Q51 V49 GRE 1: Q170 V170 Re: General question regarding parenthesis. [#permalink] ### Show Tags 12 May 2015, 20:48 Hi MarcvR, Taking FULL-LENGTH CATs is an essential part of the training process. There are things that you can learn ONLY by taking FULL CATs under realistic and test-like conditions (things that you will need to work on to improve). I highly recommend that you take a FULL CAT soon (you can download 2 for free from www.mba.com). Those score results are the only way to know if you're truly ready to take the GMAT on June 3rd. GMAT assassins aren't born, they're made, Rich _________________ 760+: Learn What GMAT Assassins Do to Score at the Highest Levels Contact Rich at: Rich.C@empowergmat.com # Rich Cohen Co-Founder & GMAT Assassin Special Offer: Save$75 + GMAT Club Tests Free
Official GMAT Exam Packs + 70 Pt. Improvement Guarantee
www.empowergmat.com/

***********************Select EMPOWERgmat Courses now include ALL 6 Official GMAC CATs!***********************

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Re: General question regarding parenthesis.  [#permalink]

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29 Jan 2018, 00:05
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Re: General question regarding parenthesis. &nbs [#permalink] 29 Jan 2018, 00:05
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# General question regarding parenthesis.

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