Question

In Python:

Write a well-documented (commented) program that asks the user for a 9-digit integer, computes its checksum, and then prints the corresponding ISBN number. The International Standard Book Number (ISBN) is a 10-digit code that uniquely specifies a book. The rightmost digit is a checksum digit that can be uniquely determined from the other 9 digits, from the condition that d1 + 2d2 +3d3 + ... + 10d10 must be a multiple of 11 (here di denotes the ith digit from the right). The checksum digit d1 can be any value from 0 to 10. The ISBN convention is to use the character X to denote 10. The checksum digit corresponding to 032149805 is 4 since 4 is the only value of x between 0 and 10 (both inclusive), for which 10·0 + 9·3 + 8·2 + 7·1 + 6·4 + 5·9 +4·8 +3·0 + 2·5 + 1·x is a multiple of 11. Sample runs would be as follows. Sample run 1: Please enter a nine digit integer: 013376940 The corresponding ISBN number would be 0133769402. Sample run 2: Please enter a nine digit integer: 013380780 The corresponding ISBN number would be 0133807800.

Answer 1

number=raw_input("Enter the number :")

digits = [(11 - i) * num for i, num in enumerate(map(int, list(number)))]

digit_11 = 11 - (sum(digits) % 11)

if digit_11 == 10:
    digit_11 = 'X'    
digits.append(digit_11)
isbn_number = "".join(map(str, digits))
print(isbn_number)