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Number properties - is 0 a multiple of every integer?

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Manager
Joined: 10 Apr 2008
Posts: 53
Number properties - is 0 a multiple of every integer?  [#permalink]

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30 Sep 2008, 23:06
I always get confused about how to think of 0. Please tell me if the following are correct -

1. 0 is neither positive nor negative.
2. 0 is even.
3. 0 is a multiple for every integer.
4. 0 is not a prime.
5. Is 0 a factor of every number? I think not but just checking.

Also,

-> Can negative numbers be prime?
-> If an int has only 2 factors then we know it is prime right away, correct?
-> Special sums in Chap 4 (page 43) only applies to consecutive integers. But not consecutive evens or consecutive primes or consecutive odd correct?
-> Average and median of consecutive numbers are equal correct??

Finally!

If faced with a very large number, is there an easy way to tell it is a prime number?? Or a multiple of 7 or 13 or 17??
All this is assuming it is not divisible by 2,3,4,5,6,8,9,10 of course.

Is there a good resource for number properties?

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Manager
Joined: 30 Sep 2008
Posts: 111
Re: Number properties - is 0 a multiple of every integer?  [#permalink]

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01 Oct 2008, 01:17
1. 0 is neither positive nor negative. -> -0 is negative, 0 is positive
2. 0 is even. -> yes, divisible by 2
3. 0 is a multiple for every integer. -> yes
4. 0 is not a prime. -> no, prime is greater than 1
5. Is 0 a factor of every number? I think not but just checking. -> no. i.e.2/0 is undefined , but every number is a factor of 0, except itself

Also,

-> Can negative numbers be prime? -> no, prime is greater than 1
-> If an int has only 2 factors then we know it is prime right away, correct? -> no, more than 2, as the factor can be 1 and itself
-> Special sums in Chap 4 (page 43) only applies to consecutive integers. But not consecutive evens or consecutive primes or consecutive odd correct? --> i dont know this sums
-> Average and median of consecutive numbers are equal correct?? -> yes, average = median = sum / 2

Finally!

If faced with a very large number, is there an easy way to tell it is a prime number?? Or a multiple of 7 or 13 or 17??
All this is assuming it is not divisible by 2,3,4,5,6,8,9,10 of course.

- try 2,3,5,7,11
- Look at the last digit of that number and guess

Is there a good resource for number properties?
Senior Manager
Joined: 04 Aug 2008
Posts: 362
Re: Number properties - is 0 a multiple of every integer?  [#permalink]

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01 Oct 2008, 06:30
Are you sure that 0 is multiple of every integer tho?

eg multiples of 18
1x2x3x3

but if u multiply by 0 you will get a 0 not 18 right?
1x2x3x3x0=0
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Joined: 30 Jun 2008
Posts: 1004
Re: Number properties - is 0 a multiple of every integer?  [#permalink]

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01 Oct 2008, 06:47
Should we not say that every integer is a multiple of 0 rather than saying 0 is a multiple of every integer ?
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Joined: 29 Aug 2007
Posts: 2420
Re: Number properties - is 0 a multiple of every integer?  [#permalink]

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01 Oct 2008, 09:00
amitdgr wrote:
Should we not say that every integer is a multiple of 0 rather than saying 0 is a multiple of every integer ?

Nope, every integer cabnnot be a multiple of 0. if so, then there will only be 0.
hOWEVER Its correct that 0 is a multiple of every integer.
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Senior Manager
Joined: 04 Aug 2008
Posts: 362
Re: Number properties - is 0 a multiple of every integer?  [#permalink]

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03 Oct 2008, 09:13
or is it vice versa?

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If you would like to discuss this question please re-post it in the respective forum. Thank you!

To review the GMAT Club's Forums Posting Guidelines, please follow these links: Quantitative | Verbal Please note - we may remove posts that do not follow our posting guidelines. Thank you.

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Re: Number properties - is 0 a multiple of every integer? &nbs [#permalink] 03 Oct 2008, 09:13
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