Write a program to find if the Number is Prime?

   1:  #include<stdio.h>

   2:  #include<conio.h>

   3:  #include<math.h>

   4:  void main()

   5:  {

   6:  int k,n,r;

   7:  int prime;

   8:  printf("Enter the num you want to test:");

   9:  scanf("%d",&n);

  10:  k=2;

  11:  while(k<=sqrt(n))

  12:  {

  13:   r=n%k;

  14:   if(r==0)

  15:   {

  16:   prime=0;

  17:   break;

  18:   }

  19:   else

  20:   k++;

  21:  }

  22:  if(prime==0)

  23:  printf("%d is not a prime num: ",n);

  24:  else

  25:  printf("%d is a prime num:",n);

  26:  getch();

  27:  }