2.6

import java.until.Scanner;
public class ComputeArea{
　　public static void main(String[] args){
　　Scanner input =new Scanner(System.in);
　　System.out.print("Enter a number between 0 and 1000: ");
　　double digits =input.nextDouble();
　　double sun =digits+digits+digits+digits;
　　System.out.println("the sun of the digits " + digits +"is" +sun);

　　}
}

2.15

import java.until.Scanner;
public class ComputeDistance{
　　public static void main(String[] args){
　　Scanner input =new Scanner(System.in);
　　System.out.print("Enter x1 and y1 : ");
　　System.out.print("Enter x2 and y2: ");
　　double point =input.nextDouble();
　　double number =(x2-x1)(x2-x1)+(y2-y1)(y2-y1);
　　double distance =Math.pow(number,0.5);
　　System.out.println("the distance between the two points " + points+"is" +distance);

　　}
}

第二章作業.