The International Standard Book Number (ISBN) is a unique numeric book identifier which is printed on every book. The ISBN is based upon a 10-digit code.
The ISBN is legal if:
1 × digit1 + 2 × digit2 + 3 × digit3 + 4 × digit4 + 5 × digit5 + 6 × digit6 + 7 × digit7 + 8 × digit8 + 9 × digit9 + 10 × digit10 is divisible by 11.
Example:
For an ISBN 1401601499
Sum = 1 × 1 + 2 × 4 + 3 × 0 + 4 × 1 + 5 × 6 + 6 × 0 + 7 × 1 + 8 × 4 + 9 × 9 + 10 × 9 = 253 which is divisible by 11.
Write a program to:
import java.util.Scanner;
public class RAnsariISBNCheck
{
public static void main(String args[]) {
Scanner in = new Scanner(System.in);
System.out.print("Enter the ISBN: ");
long isbn = in.nextLong();
int sum = 0, count = 0, m = 10;
while (isbn != 0) {
int d = (int)(isbn % 10);
count++;
sum += d * m;
m--;
isbn /= 10;
}
if (count != 10) {
System.out.println("Illegal ISBN");
}
else if (sum % 11 == 0) {
System.out.println("Legal ISBN");
}
else {
System.out.println("Illegal ISBN");
}
}
}Enter the ISBN: 1401601499
Legal ISBN
Press any key to continue . . .
Enter the ISBN: 140166444
Illegal ISBN
Press any key to continue . . .
First read the algorithm, then study the program code line by line. After that, compare the code with the output and finally go through the explanation. This approach helps learners understand both the logic and the implementation properly.
After understanding this example, try to rewrite the same program without looking at the code. Then change some values or logic and run it again. This helps improve confidence and keeps learners engaged on the page for longer.