Chapter 3 Exercise 9, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

**3.9 (Business: check ISBN-10) An ISBN-10 (International Standard Book Number) consists of 10 digits: d1d2d3d4d5d6d7d8d9d10. The last digit, d10, is a checksum, which is calculated from the other nine digits using the following formula: (d1 * 1 + d2 * 2 + d3 * 3 + d4 * 4 + d5 * 5 + d6 * 6 + d7 * 7 + d8 * 8 + d9 * 9) % 11 If the checksum is 10, the last digit is denoted as X according to the ISBN-10 convention. Write a program that prompts the user to enter the first 9 digits and displays the 10-digit ISBN (including leading zeros). Your program should read the input as an integer. Here are sample runs:

import java.util.Scanner;
 
public class ProgrammingEx3_9 {
 
 public static void main(String[] args) {
  Scanner input = new Scanner(System.in);
 
  System.out.print("Enter the first 9 digits of an ISBN as integer:");
  int isbn = input.nextInt();
  int d1 = isbn / 100000000;
  int d2 = (isbn % 100000000) / 10000000;
  int d3 = (isbn % 10000000) / 1000000;
  int d4 = (isbn % 1000000) / 100000;
  int d5 = (isbn % 100000) / 10000;
  int d6 = (isbn % 10000) / 1000;
  int d7 = (isbn % 1000) / 100;
  int d8 = (isbn % 100) / 10;
  int d9 = (isbn % 10);
 
  int d10 = (d1 * 1 + d2 * 2 + d3 * 3 + d4 * 4 + d5 * 5 + d6 * 6 + d7 * 7
    + d8 * 8 + d9 * 9) % 11;
 
  System.out.print("The ISBN-10 number is " + d1 + d2 + d3 + d4 + d5 + d6
    + d7 + d8 + d9);
 
  if (d10 == 10) {
   System.out.print('X');
  } else {
   System.out.print(d10);
  }
 
 }
 
}