Goldbach Number is a number which can be expressed as sum of two odd prime numbers.
Example 1: 50. 3+47 = 50. Hence it is a Goldbach Number.
Example 2: 7. Since it can not be expressed as sum of odd prime pairs it is not a Goldbach Number.
Java
import java.util.*;
public class GoldbachNumber
{
public static void main(String args[])
{
int n=0,j=0,flag=0;
Scanner sc=new Scanner(System.in);
System.out.print("Enter a number: ");
n=sc.nextInt();
for(int i=3;i<=n;i=i+2)
{
j=n-i;
flag=0;
for(int k=2;k<i;k++)
{
if(i%k==0)
{
flag++;
break;
}
}
for(int k=2;k<j;k++)
{
if(j%k==0)
{
flag++;
break;
}
}
if(flag==0&&j%2!=0)
{
System.out.println(n+" is a Goldbach Number");
System.exit(1);
}
}
System.out.println(n+" is not a Goldbach Number");
}
}