Computer Science for IGCSE & O level - Data Transmission (Section 3 - No. 25)
How is the check digit calculated in the ISBN-13 system?
By dividing the sum of the first 12 digits by 11.
By using a modulo 10 operation on a weighted sum of the first 12 digits.
By adding all the digits together and taking the last digit of the sum.
By multiplying the sum of the first 12 digits by a prime number.
Explication
The ISBN-13 check digit calculation involves a weighted sum (alternating weights of 1 and 3) of the first 12 digits, and then applying a modulo 10 operation.