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# An odd number added to itself an odd number of times yields

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An odd number added to itself an odd number of times yields  [#permalink]

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Updated on: 05 Jul 2019, 04:22
00:00

Difficulty:

45% (medium)

Question Stats:

48% (00:45) correct 52% (00:47) wrong based on 95 sessions

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An odd number added to itself an odd number of times yields

(A) an odd number
(B) an even number
(C) a prime number
(D) a positive number
(E) a perfect square

Source: Nova GMAT
Difficulty Level: 650

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Originally posted by Bunuel on 17 Jun 2017, 06:04.
Last edited by SajjadAhmad on 05 Jul 2019, 04:22, edited 1 time in total.
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Re: An odd number added to itself an odd number of times yields  [#permalink]

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17 Jun 2017, 06:08
The number will be added an even number of times,or multiplied by an even number of times.

B EVEN Number.

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Re: An odd number added to itself an odd number of times yields  [#permalink]

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17 Jun 2017, 06:22
Bunuel wrote:
An odd number added to itself an odd number of times yields

(A) an odd number
(B) an even number
(C) a prime number
(D) a positive number
(E) a perfect square

Assume the odd number to be 1
If it is added to itself 3 times(again odd), the sum is 3(which is odd)
Hence, Option A is the correct answer
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Re: An odd number added to itself an odd number of times yields  [#permalink]

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17 Jun 2017, 07:58
Bunuel wrote:
An odd number added to itself an odd number of times yields

(A) an odd number
(B) an even number
(C) a prime number
(D) a positive number
(E) a perfect square

Plug in some numbers and check -

3 + 3 + 3 = 9
5 + 5 + 5 + 5 + 5 = 25
7 + 7 + 7 + 7 + 7 + 7 + 7 = 49

Thus, the result will always be ODD, hence answer will be (A) an Odd Number.
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Re: An odd number added to itself an odd number of times yields  [#permalink]

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18 Jun 2017, 03:22
The number property being checked is as follow:

1. Sum of two odd numbers is even
2. Sum of three odd numbers is odd.
3. Sum of four odd numbers is even

Conclusion: Sum of odd number of odd numbers is odd. While, sum of even number of odd numbers is even.
Example: Sum of 3 odd nos. is odd. Sum of 4 odd nos. is even

Confusion in the question, although GMAT may not test the language's dubiousness:

Consider an odd number 3: 3
Now, add 3 once to 3: 3 + 3 = 6, even
Now, add 3 twice to itself 3 + 3 + 3 = 9 odd.
Now, add t thrice to itself 3(the original number) + Three three [3 + 3 + 3\ = 12, even

So, as per the question's language, an odd number added odd number of times to itself will give an even number as a result. (The original property being; Sum of even number of odd numbers is even)
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Re: An odd number added to itself an odd number of times yields  [#permalink]

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18 Jun 2017, 08:46
Shouldn't it be like odd number + odd number ( odd number of times)

3+3= 6
3+3+3+3 = 12

So B, an even number.

Abhishek009 wrote:
Bunuel wrote:
An odd number added to itself an odd number of times yields

(A) an odd number
(B) an even number
(C) a prime number
(D) a positive number
(E) a perfect square

Plug in some numbers and check -

3 + 3 + 3 = 9
5 + 5 + 5 + 5 + 5 = 25
7 + 7 + 7 + 7 + 7 + 7 + 7 = 49

Thus, the result will always be ODD, hence answer will be (A) an Odd Number.
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Re: An odd number added to itself an odd number of times yields  [#permalink]

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18 Jun 2017, 08:56
Bunuel wrote:
An odd number added to itself an odd number of times yields

(A) an odd number
(B) an even number
(C) a prime number
(D) a positive number
(E) a perfect square

Rule 1: Sum of odd number of odd numbers (ie; sum of 3 odd numbers, sum of 5 odd numbers etc) is always odd.
Rule 2: Sum of even number of odd numbers (ie; sum of 2 odd numbers, sum of 4 odd numbers etc) is always even.

Therefore An odd number added to itself an odd number of times yields odd number.

To check this rule: Lets try

$$3 + 3 + 3 = 9$$

$$3 + 3 + 3 + 3 + 3 = 15$$

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Re: An odd number added to itself an odd number of times yields  [#permalink]

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18 Jun 2017, 11:31
IMO, B

This is a tricky question just because it can be interpreted multiple ways.

Let's take 3

3 + 3 (added an odd # of times, in this case 1) = 6

3 + 3 + 3 + 3 (added 3 times) = 12
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Re: An odd number added to itself an odd number of times yields  [#permalink]

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18 Jun 2017, 11:37
achuepnlx wrote:
Shouldn't it be like odd number + odd number ( odd number of times)

3+3= 6
3+3+3+3 = 12

So B, an even number.

Bunuel wrote:
An odd number added to itself an odd number of times yields

The red part is not in accordance with the condition stated in the question , you are adding an ODD number EVEN number of times....

Hope this helps..
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Re: An odd number added to itself an odd number of times yields  [#permalink]

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18 Jun 2017, 11:50
Abhishek009 wrote:
achuepnlx wrote:
Shouldn't it be like odd number + odd number ( odd number of times)

3+3= 6
3+3+3+3 = 12

So B, an even number.

Bunuel wrote:
An odd number added to itself an odd number of times yields

The red part is not in accordance with the condition stated in the question , you are adding an ODD number EVEN number of times....

Hope this helps..[/b

Yea that's why I said this question is difficult bc it's hard to interpret. Is it added an odd number of times to the original number or overall added together an odd number of times?

Hopefully they wouldn't put such a question on the real test

[b]Posted from my mobile device
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Re: An odd number added to itself an odd number of times yields  [#permalink]

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09 Oct 2018, 21:53
I really don't like how this question is worded. I feel like you could interpret it as 3 + 3 is adding three to itself ONCE.
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Re: An odd number added to itself an odd number of times yields  [#permalink]

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03 Nov 2018, 11:37
This questions is worded incorrectly in my opinion if the answer is to be A.

If you add an odd number with itself 0 times, then the answer is just the odd number itself. Once you add the odd number with itself for the first time, it becomes even. Answer should be B IMO.
Re: An odd number added to itself an odd number of times yields   [#permalink] 03 Nov 2018, 11:37
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