Please provide clear explanation for the following question: 1. class Main {public static void main(String[]args){ n(0,5,10); } public static void outPut (int num1 , int num2, int num3){ while (num

Please provide clear explanation for the following question: 

1. class Main {public static void main(String[]args){

n(0,5,10);

}

public static void outPut (int num1 , int num2, int num3){

while (num3 > num1 || num3 > num2){

num1 = num1 + num2;

num2 = num2 * 2;

System.out.print(num1 + " " + num2 + " ");

}

System.out.println();

}

}

Why is the output 5 10 15 20, instead of just 15 20?

2. how to classify when a math expression result  is double or int?

3. different between good boolean zen style and bad boolean zen style.