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M04 #10 [#permalink] New post 25 Dec 2008, 13:27
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Question Stats:

35% (01:21) correct 64% (00:23) wrong based on 0 sessions
What is the value of X ?

1. X! is odd
2. X is even

[Reveal] Spoiler: OA
C

Source: GMAT Club Tests - hardest GMAT questions

In this partcular problem the OA is C. according to me it should be A.

From S1 we get x=0 or x=1. 0 is even in GMAT, Hence only value of x is 1, sufficient.
[Reveal] Spoiler: OA
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Re: M04: Question 15 [#permalink] New post 25 Dec 2008, 23:15
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Stmt1 does not say that x is odd. It says factorial of x is odd. And this is true for both x = 0 and x = 1. Hence, stmt1 by itself is insufficient.
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Re: M04: Question 15 [#permalink] New post 26 Dec 2008, 02:49
Thanks scthakur.
I wrongly thogh factorial of 0 is 0.
Later found out it is 1
Thanks again.
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Re: M04 #10 [#permalink] New post 22 May 2010, 07:43
Initially I jumped to A as I forgot 0!=1. Thanks a lot. This one is really good.
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Re: M04 #10 [#permalink] New post 22 May 2010, 12:12
i think the trick here is not to recall that factorial of zero is one
making two correct values for statement1.

Even numbers N = 2n (n=0,1,2, 3...) That is 0,2,4,6 are all even numbers
OA is C, as stmt2 has clarified that X is even (i.e 0)
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Re: M04 #10 [#permalink] New post 22 May 2010, 22:10
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statement 1:
===========
X can either be Zero or One since both the factorial values are odd.So insuff.


Statement 2:
==========
X is even.Certainly insuff.

combining both,we get X = 0.so suff.

I will go with option C
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Re: M04 #10 [#permalink] New post 23 May 2010, 02:49
Statement 1 impliies x can be 0 or 1..so not sufficient.
Statement 2 x is even...not sufficient.
Combining 1 & 2 x = 0,
hence C
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Re: M04 #10 [#permalink] New post 24 May 2010, 00:04
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I say answer is C

1) X! is odd. 0! is 1 and 1! is 1. You have two options.

2) X is an even number. 0 is considered an even number.

So 0 is the value of X.
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Re: M04 #10 [#permalink] New post 19 Jun 2010, 23:43
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kevinw1081 wrote:
Are all factorials even? except for 1?

All factorials are even, except for 0 and 1 whose factorials are odd and the same; 0! = 1! = 1.
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Re: M04 #10 [#permalink] New post 03 Jul 2010, 14:45
gattupalli wrote:
I completely agree with Adhiraj even I assume that 0 is not even either but the answer says is C. My answer was E too... should I take it like a thumb rule that 0 is even in GMAT?

Even = 2n.
where n: {0, 1, 2, ...}
list of even nos: {0, 2, 4, ...} - 0 is inclusive.
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Re: M04 #10 [#permalink] New post 05 Jul 2010, 02:14
Zero fits the definition of "even number": it is an integer multiple of 2.
Source: wiki
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Re: M04 #10 [#permalink] New post 20 Aug 2010, 00:44
Its C.

1 => 0 or 1
2 => 0,2,4....

So C specifies 0 as the answer.
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Re: M04 #10 [#permalink] New post 12 Nov 2010, 20:30
0!=1

Oh boy... I totally forgot about this. I too thought 0!=0 /sadface.
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Re: M04 #10 [#permalink] New post 25 May 2011, 04:27
The answer is C.

(1) says x can be 0 or 1, where x! = 1

Insufficient

(2) says x is even

Insufficient

So (1) + (2) = 0

Sufficient.
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Re: M04 #10 [#permalink] New post 25 May 2011, 09:55
Clean bowled on this one! I guess I learned two things here.

1. 0! = 1, 0! & 1! are the only Odd factorials
2. 0 is an Even number (this was a surprise!)

I also think that the key is too look out for answer choices that seem 'too good to be true'; 95% of the time in such instances, the GMAT is playing around with you.
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Re: M04 #10 [#permalink] New post 29 May 2011, 04:25
Caught the 0! = 1 and 1! = 1 but it took me a while to realize that 0 is even.
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Re: M04 #10 [#permalink] New post 29 May 2012, 06:31
Statement 1 is sufficient because it results in one answer....that's 0!=1; and 1!=1 and 1 is odd.
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Re: M04 #10 [#permalink] New post 29 May 2012, 06:44
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Cosmas wrote:
Statement 1 is sufficient because it results in one answer....that's 0!=1; and 1!=1 and 1 is odd.


Welcome to GMAT Club. Note that the answer to this question is C, not A.

What is the value x ?

(1) x! is odd --> two values satisfy this condition 0 and 1: 0!=1 and 1!=1. Not sufficient.

(2) x is even --> x can be any even number. Not sufficient.

(1)+(2) Since from (1) x is either 0 or 1 and (2) says that x is even then x=0=even. Sufficient.

Answer: C.

Hope it's clear.
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Re: M04 #10 [#permalink] New post 29 May 2012, 06:53
Thanks mate. i see now.lol


Bunuel wrote:
Cosmas wrote:
Statement 1 is sufficient because it results in one answer....that's 0!=1; and 1!=1 and 1 is odd.


Welcome to GMAT Club. Note that the answer to this question is C, not A.

What is the value x ?

(1) x! is odd --> two values satisfy this condition 0 and 1: 0!=1 and 1!=1. Not sufficient.

(2) x is even --> x can be any even number. Not sufficient.

(1)+(2) Since from (1) x is either 0 or 1 and (2) says that x is even then x=0=even. Sufficient.

Answer: C.

Hope it's clear.
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Re: M04 #10 [#permalink] New post 29 May 2012, 19:15
Good question...
The answer is C and many people have already explained it.
A small information regarding even and odd numbers. Even and odd numbers are defined for integers ie., -2,-4 etc are also even numbers. So, zero is obviously an even number.
E = {...-4,-2,0,2,4...}
O = {..-3,-1,1,3...}

PS: I am new to the forum and this is my first post..:)
Re: M04 #10   [#permalink] 29 May 2012, 19:15
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