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Author Topic: Freaky question........:P  (Read 10307 times)

Offline Deadly_king

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Freaky question........:P
« on: October 01, 2010, 05:52:05 am »
What smallest number is to be multiplied to 722 to obtain a square number?

The answer is obviously 2. However this question was to be attempted under exam conditions without the use of a calculator.

I feel rather uncomfortable asking for such a silly question but I think its worth it.
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elemis

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Re: Freaky question........:P
« Reply #1 on: October 01, 2010, 05:57:03 am »
Was this in a CIE or Edexcel paper ?
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Offline Ukhti-R

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Re: Freaky question........:P
« Reply #2 on: October 01, 2010, 11:14:35 am »
Let the number be x.

? 722x must equal to a number to the square.
Find the multiples of 722.

722/2 = 361

Look for a number to divide 361 with. Isn't an even number, nor is it 3, then it has to be a prime number.

361/19 = 19

So, the multiples of 722 = 19^2 * 2

For 722 to be a squared number, 2 has to be to the power of 2 too.
>>> ? 722x =? 19^2 * 2^2
>>> x = 2.


;D
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Offline Deadly_king

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Re: Freaky question........:P
« Reply #3 on: October 01, 2010, 05:44:56 pm »
Quote from: Jump! on October 01, 2010, 11:14:35 am
Let the number be x.

? 722x must equal to a number to the square.
Find the multiples of 722.

722/2 = 361

Look for a number to divide 361 with. Isn't an even number, nor is it 3, then it has to be a prime number.

361/19 = 19

So, the multiples of 722 = 19^2 * 2

For 722 to be a squared number, 2 has to be to the power of 2 too.
>>> ? 722x =? 19^2 * 2^2
>>> x = 2.


;D
Thanks dude........that was really helpful :)
+rep.....after i spread the love

Neither one Ari.........it was just a test at school level :P
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Offline Ukhti-R

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Re: Freaky question........:P
« Reply #4 on: October 01, 2010, 10:12:39 pm »
Okay okay. That wasn't me ::)

I wouldn't be able to answer such a question.

It was your lovely Mauritius friend Alpha who Facebook messaged me the answer to reply to you. +Rep her, not me (:
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"...And whosoever fears Allah and keeps his duty to Him, He will make a a way for him to get out (from every difficulty). And He will provide him from (sources) he never could imagine. And whosoever puts his trust in Allah, then He will suffice him." [65: 2-3]

Freaked12

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Re: Freaky question........:P
« Reply #5 on: October 02, 2010, 01:02:46 am »
If Alpha read that post, why has she banned herself? :P

She doesnt trust her self  yet

Anyway

you need to get the multiples of the number
then see what multiply need a second one to give you two sets of identical multiples

722=2*19*19

so you need the second 2 to get two sets of multiples
(2*19)(2*19)

p.s. if you could see 19 was the square root of 361 without a calculator, your brain works better than mine
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Offline Deadly_king

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Re: Freaky question........:P
« Reply #6 on: October 02, 2010, 04:05:40 am »
Quote from: Jump! on October 01, 2010, 10:12:39 pm
Okay okay. That wasn't me ::)

I wouldn't be able to answer such a question.

It was your lovely Mauritius friend Alpha who Facebook messaged me the answer to reply to you. +Rep her, not me (:

Ooh.........alright then.

Yeah......I know she's pretty busy with her exams and all that. Thank You Alpha :)
I know you're going to see this post :P

But Requiem has a point there.............it's not something we know by heart.......I mean 19*19=361.
Manually it takes a whole lot of time ;)

Nope Requiem........Alpha has full confidence in herself. Am pretty sure about that but sometimes you need not take too much risks  :P
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Offline Ukhti-R

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Re: Freaky question........:P
« Reply #7 on: October 02, 2010, 04:25:31 pm »
And about finding the square root of 361:

We know 15*15= 225 and 20*20= 400. We'll use them as landmarks.

Therefore, 15 < ./ 361 < 20

Possibilities: 16, 17, 18, 19.

An even number is one which can be divided by 2 => any number multiplied by an even number will necessarily give an even number.

From the above, we can eliminate 16 and 18 since 361 is odd.
7*7 will give 49, 361 ends with 1, so 17 cannot be the required number. 9*9 gives 81, it corresponds to 361.

Conclusion reached by logical procedures, which means you need not know the multiplications by heart. But you sure need a good brain. ;)

N.B ./ is used for the root sign.

;D
AND ROXY STRIKES AGAIN :P

Hope I answered your question with my amazing math skills :)
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"...And whosoever fears Allah and keeps his duty to Him, He will make a a way for him to get out (from every difficulty). And He will provide him from (sources) he never could imagine. And whosoever puts his trust in Allah, then He will suffice him." [65: 2-3]

Offline Deadly_king

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Re: Freaky question........:P
« Reply #8 on: October 02, 2010, 04:28:07 pm »
Quote from: Jump! on October 02, 2010, 04:25:31 pm
And about finding the square root of 361:

We know 15*15= 225 and 20*20= 400. We'll use them as landmarks.

Therefore, 15 < ./ 361 < 20

Possibilities: 16, 17, 18, 19.

An even number is one which can be divided by 2 => any number multiplied by an even number will necessarily give an even number.

From the above, we can eliminate 16 and 18 since 361 is odd.
7*7 will give 49, 361 ends with 1, so 17 cannot be the required number. 9*9 gives 81, it corresponds to 361.

Conclusion reached by logical procedures, which means you need not know the multiplications by heart. But you sure need a good brain. ;)

N.B ./ is used for the root sign.

;D
AND ROXY STRIKES AGAIN :P

Hope I answered your question with my amazing math skills :)

hehe.....this explanation is much clearer :)

Indeed you have undoubted skills........but who must I +rep for this one??? :P
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Freaked12

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Re: Freaky question........:P
« Reply #9 on: October 02, 2010, 11:29:18 pm »
Just +rep Jump man.


For Her awesomeness  ;)


-Requiem
« Last Edit: October 02, 2010, 11:36:35 pm by Requiem »
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Offline Deadly_king

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Re: Freaky question........:P
« Reply #10 on: October 03, 2010, 04:59:52 am »
Quote from: Requiem on October 02, 2010, 11:29:18 pm
Just +rep Jump man.


For Her awesomeness  ;)


-Requiem
hmm......i just wanted to know if this one was from Alpha too?
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Offline Ukhti-R

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Re: Freaky question........:P
« Reply #11 on: October 03, 2010, 07:57:48 pm »
Huhh ? Alphaaa ? Does she exist ?


:P
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"...And whosoever fears Allah and keeps his duty to Him, He will make a a way for him to get out (from every difficulty). And He will provide him from (sources) he never could imagine. And whosoever puts his trust in Allah, then He will suffice him." [65: 2-3]

Offline Deadly_king

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Re: Freaky question........:P
« Reply #12 on: October 04, 2010, 05:03:39 am »
Quote from: Jump! on October 03, 2010, 07:57:48 pm
Huhh ? Alphaaa ? Does she exist ?


:P
Alright....i'll + rep you then  ;)
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Offline Ukhti-R

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Re: Freaky question........:P
« Reply #13 on: October 04, 2010, 04:52:32 pm »
Quote from: Deadly_king on October 04, 2010, 05:03:39 am
Alright....i'll + rep you then  ;)

noooooooooooo. + rep alpha when she comes back (:
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"...And whosoever fears Allah and keeps his duty to Him, He will make a a way for him to get out (from every difficulty). And He will provide him from (sources) he never could imagine. And whosoever puts his trust in Allah, then He will suffice him." [65: 2-3]

Offline Deadly_king

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Re: Freaky question........:P
« Reply #14 on: October 04, 2010, 05:34:21 pm »
Quote from: Jump! on October 04, 2010, 04:52:32 pm
noooooooooooo. + rep alpha when she comes back (:

Hey I understood it was Alpha's work ;)

I had already + repd for the first answer.

Now I +rep you for being a good intermediate  :P
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