import java.util.*;
import java.io.*;
public class TEster {
/**
* @param args
*/
public static void main(String[] args) {
int x;
char Guess;
Scanner Number_input = new Scanner( System.in );
System.out.println("Enter a number: ");
x = Number_input.nextInt();
if (x >=50) {
Guess = 'Y';
}
else if (x <=50) {
Guess = 'N';
System.out.print("Number:" + Guess);
}
}
}
If you look at your if/else if statement, you'll see your problem. What happens when you enter a number higher than 50? What happens when you enter a number lower than 50? What happens when you enter 50 itself? I suggest reading
The if-then and if-then-else Statements (The Java™ Tutorials > Learning the Java Language > Language Basics) for more info about it.