9 has no factor of 2 so N

9 has no factor of 2 so N must be divisible by 8 Let it be 8a where a ≥ 1 Now as per the question there shd be one prime number between 8a and 9a For a =1, there is no number a=2 , we have 17 a prime number So the answer is 16.

To cont your assumptionFor

To cont your assumption For a=3 the number are 24, 25, 26 & 27 and none of them are prime. So its wrong. I am not going to prove it but this is one of the great works of Joseph Bertrand and according to him if n is an integer greater than 3, then there is at least one prime between n and 2n-2 Few other important points are

• If n is at least 48, then there is at least one prime between n and 9n/8.
• If n is greater than 6, then there is at least one prime of theform 4k+1 and at least one of the form 4k+3 between n and 2n.
• If n is greater than or equal to 118, then the interval n to 4n/3 inclusive contains a prime of each of the forms 4n+1, 4n-1, 6n+1, and 6n-1.
• If n is greater than 15, then there is at least one number between n and 2n that is the product of three different primes.

y cant d answer be 10???

y cant d answer be 10???

n and 9n/8 means between 10 and 11.25, right...
11 is a prime number....
so 10 can b d answer, right???

Simply because 11.25 is not

Simply because 11.25 is not an integer

does the question specify

does the question specify dat it shud be an integer?

Prime number question

The answer is very simple.It is clear that n/8 should be an integer.Taking n/8=1,I get no prime number between 8 & 9.Then assuming n/8=2,I get a prime number 17 between 16 & 18,i.e.,between n & 9n/8.So, the correct answer is "n=2".

Prime number question

The answer is very simple.It is clear that n/8 should be an integer.Taking n/8=1,I get no prime number between 8 & 9.Then assuming n/8=2,I get a prime number 17 between 16 & 18,i.e.,between n & 9n/8.So, the correct answer is "n=2".

The Answer Should

The answer should be guessed first that it is an integer or not,so what are the options anyway???