Question

(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 convention. Write a program that prompts the user to enter the first 9 digits as a string and displays the 10-digit ISBN (including leading zeros). Your program should read the input as a string. Here are sample runs: Enter the first 9 digits of an ISBN-10 as a string:013601267 The ISBN-10 number is 0136012671 Enter the first 9 digits of an ISBN-10 as a string:013031997 The ISBN-10 number is 013031997X

Answer 1

Answer:

 The solution code is written in Python 3

1. digits = input("Enter 9 digits: ")
3. multiplier = 1
4. total = 0
6. for x in digits:
7.    total += int(x) * multiplier  
8.    multiplier += 1
10. checksum = total % 11  
12. if(checksum == 10):
13.    print(digits + "X")
14. else:
15.    print(digits + str(checksum))

Explanation:

Firstly, use input function to get user input for 9 digits (Line 1)

Next we can use a for-loop to estimate the summation (d1 * 1 + d2 * 2 + d3 * 3 + d4 * 4 + d5 * 5+ d6 * 6 + d7 * 7 + d8 * 8 + d9 * 9) ( Line 6-8)

Then only apply % operator to get the remainder of total and get the checksum (Line 10)

Next create if and else statement to print the digits string joined with X if checksum is 10 else join digits string with checksum value (Line 12 -15)