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GMATClub Diagnosis Questions wrong?

by sunman » Wed Dec 28, 2011 6:42 pm
Alright, so this is getting really frustrating.

The answer key says that #1 could be 1, 2, 3, 4, or 0.

How can #1 be 0!, since 0! IS divisible by 5???? This is driving me up a wall. Is there something I'm missing, or are these questions just busted up?

Edit: The question is supposed to say: Is N divisible by 5?

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by pemdas » Wed Dec 28, 2011 7:14 pm
factorial of 0 is 1 not 0
sunman wrote:Alright, so this is getting really frustrating.

The answer key says that #1 could be 1, 2, 3, 4, or 0.

How can #1 be 0!, since 0! IS divisible by 5???? This is driving me up a wall. Is there something I'm missing, or are these questions just busted up?

Edit: The question is supposed to say: Is N divisible by 5?

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by sunman » Wed Dec 28, 2011 7:17 pm
pemdas wrote:factorial of 0 is 1 not 0
sunman wrote:Alright, so this is getting really frustrating.

The answer key says that #1 could be 1, 2, 3, 4, or 0.

How can #1 be 0!, since 0! IS divisible by 5???? This is driving me up a wall. Is there something I'm missing, or are these questions just busted up?

Edit: The question is supposed to say: Is N divisible by 5?

Image

Grrr....ok, how does that work? I've never dealt with 0 factorial before.

3! = 3x2x1
2! = 2x1
1! = 1x1?
0! = 0x1?

I don't get it.
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by pemdas » Wed Dec 28, 2011 7:20 pm
brrrrrr
1!=1
0!=1

they are not asking if N! is divisible by 5, rather N or 0

N! isn't divisible by 5 in st(1) implies N can be 0,1,2,3,4 and among these N=0 is divisible by 5

st(2) implies two numbers in unit's digit 0 and 9

combined two st-s imply only 0 and answer Yes, divisible Suff
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by sunman » Wed Dec 28, 2011 8:18 pm
pemdas wrote:brrrrrr
1!=1
0!=1

they are not asking if N! is divisible by 5, rather N or 0

N! isn't divisible by 5 in st(1) implies N can be 0,1,2,3,4 and among these N=0 is divisible by 5

st(2) implies two numbers in unit's digit 0 and 9

combined two st-s imply only 0 and answer Yes, divisible Suff
That's a garbage question that won't even be in the real GMAT.

Thank you though, I appreciate your expertise.

I still don't get the concept of "0 factorial". I doubt the GMAT would test on something so nebulous. This is my 3rd shot at the GMAT.
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by neelgandham » Thu Dec 29, 2011 3:56 am
sunman : See if this -> https://www.adonald.btinternet.co.uk/Factor/Zero.html and this https://www.zero-factorial.com/whatis.html answer your question
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by Brent@GMATPrepNow » Thu Dec 29, 2011 8:29 am
sunman wrote: I doubt the GMAT would test on something so nebulous.
I agree that it's unlikely that you'd be tested directly on your knowledge of whether or not 0!=1.
However, you are tested on this indirectly when you use certain counting formulas.

For example, 3C3=3!/[(3!)(0!)]
Here, we need to know that 0!=1

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by sunman » Thu Dec 29, 2011 9:28 am
Thanks guys, you're the best.

0!, what a stupid concept...haha

I swear to you, once I get that 49+ on quant, I'm never touching bloody freaking mathematics again. I got through my entire undergrad career without taking a single math class.

Alright...so my first try I got a 6/46/40 for a 700, 2nd try I had a disappointingly modest improvement at 6/47/41 for 710.

What does a similiarly modest improvement of 6/48/42 come out to?

800score's GMAT calculator says 750, but I think it's formula may be dubious.

Best case scenario I can pull a 49+ on quant and 42+ on verbal for something near a 750...but we'll see. Traditionally struggle on quant, and usually run dry on time. Even on the MGMAT tests, I rarely ever broke 48.
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by Brent@GMATPrepNow » Thu Dec 29, 2011 9:39 am
sunman wrote:What does a similiarly modest improvement of 6/48/42 come out to?
800score's GMAT calculator says 750, but I think it's formula may be dubious.
750 seems a bit high.

This post suggests that 48Q + 42V = 730: https://www.beatthegmat.com/done-730-48q-42v-t42464.html

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by sunman » Thu Dec 29, 2011 9:52 am
Brent@GMATPrepNow wrote:
sunman wrote:What does a similiarly modest improvement of 6/48/42 come out to?
800score's GMAT calculator says 750, but I think it's formula may be dubious.
750 seems a bit high.

This post suggests that 48Q + 42V = 730: https://www.beatthegmat.com/done-730-48q-42v-t42464.html

Cheers,
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Ugh...if I could only keep my GMATPrep1 performance of 50/45 (770) :-D
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by Brent@GMATPrepNow » Thu Dec 29, 2011 9:56 am
sunman wrote:Ugh...if I could only keep my GMATPrep1 performance of 50/45 (770) :-D
If you did it once, you can do it again!! :-)

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by neelgandham » Thu Dec 29, 2011 11:50 am
sunman wrote: What does a similiarly modest improvement of 6/48/42 come out to?
Q48 V42 - 730
Q49 V42 - 740/750
Q50 V42 - 750/760
Q50 V43 - 760
Q51 V42 - 760/770

Source: Previous scores. Hope it helps !
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by [email protected] » Sat Jan 21, 2012 10:14 pm
I completely understood the question but I did not get this point:

how is 0 divisible by 9

from that perspective, 0 is divisible by every number....

I also got the first statement of this question!!!

Can anyone plss help...
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