Question

CIS- Python

(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).

Sample Run 1

Enter the first 9 digits of an ISBN as a string: 3601267

Incorrect input. It must have exact 9 digits

Sample Run 2

Enter the first 9 digits of an ISBN as a string: 013601267

The ISBN-10 number is 0136012671

Sample Run 3

Enter the first 9 digits of an ISBN as a string: 013031997

The ISBN-10 number is 013031997X

If you get a logical or runtime error, please refer https://liangpy.pearsoncmg.com/faq.html.

Answer 1

# Reading input
s = input("Enter the first 9 digits of an ISBN-10 as a string: ")
if(len(s)==9):
    # Initializing count to 1
    count = 0
    # looping through each digit of the input
    for i in range(1,10):
        # Counting dx*x for digit dx
        count += (i*(ord(s[i-1])-ord('0')))
    # Calculating the reminder
    count = count % 11
    # If count is less than 10 then appending reminder at the end
    if(count < 10):
        s += str(count)
    # If count is greater than or equals to 10 then appending X at the end
    else:
        s += "X"
    # Printing the final value of s
    print("The ISBN-10 number is",s)
else:
    print("Incorrect input. It must have exact 9 digits")