I found this in GMAT Prep Now Data Sufficiency.
I just want to understand it.
If K is an integer greater than 1, and S is the sum of all positive divisors of K, is S > K+1?
So in GMAT Prep Now Video, they paraphrased it to "Is K not prime?"
I just wanted to know how one can tell using give information that K is not prime.
Thanks!
Prime and Composite
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Prime numbers are defined as the numbers whose only positive divisors are 1 and the number itself.sparkles3144 wrote:I found this in GMAT Prep Now Data Sufficiency.
I just want to understand it.
If K is an integer greater than 1, and S is the sum of all positive divisors of K, is S > K+1?
So in GMAT Prep Now Video, they paraphrased it to "Is K not prime?"
I just wanted to know how one can tell using give information that K is not prime.
Thanks!
Sum of all positive divisors of a prime number, lets say k is therefore: 1+k;
s=1+k for all primes
For non-primes, you must have at least 1 more positive divisor, so in that case:
s>1+k for all non-primes
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- Senior | Next Rank: 100 Posts
- Posts: 38
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Prime numbers are defined as the numbers whose only positive divisors are 1 and the number itself.sparkles3144 wrote:I found this in GMAT Prep Now Data Sufficiency.
I just want to understand it.
If K is an integer greater than 1, and S is the sum of all positive divisors of K, is S > K+1?
So in GMAT Prep Now Video, they paraphrased it to "Is K not prime?"
I just wanted to know how one can tell using give information that K is not prime.
Thanks!
Sum of all positive divisors of a prime number, lets say k is therefore: 1+k;
s=1+k for all primes
For non-primes, you must have at least 1 more positive divisor, so in that case:
s>1+k for all non-primes