/*
 * ISBNDigit.java
 *
 * Program to calculate the 10th digit of an 
 * ISBN number given the first 9
 *
 * Nadeem Abdul Hamid
 * CS120A - Fall 2004
 *
 */

public class ISBNDigit {
    
    public static void main(String args[]) {
        System.out.print("Please enter first 9 digits of ISBN number: ");
        int nineDig = Keyboard.readInt();
        
        int temp = nineDig;
        int sum = (temp % 10)*2;         // add one digit
        temp /= 10;
        sum += (temp % 10)*3;            // second digit
        temp /= 10;
        sum += (temp % 10)*4;            // third digit
        temp /= 10;
        sum += (temp % 10)*5;            // 4th digit
        temp /= 10;
        sum += (temp % 10)*6;            // 5th digit
        temp /= 10;
        sum += (temp % 10)*7;            // 6th digit
        temp /= 10;
        sum += (temp % 10)*8;            // 7th digit
        temp /= 10;
        sum += (temp % 10)*9;            // 8th digit
        temp /= 10;
        sum += (temp % 10)*10;            // 9th digit
        
        int lastDig = (11 - (sum % 11)) % 11;

        System.out.print("The last digit should be: ");
        if (lastDig == 10) System.out.println("X");
        else System.out.println(lastDig);
    }
    
    
}