This is because a value of one multiplied by 89 (sum of weights) is 89, and 89 divided by 11 is 8 with remainder 1/11; thus 1 is the check digit.
This is. A value of one multiplied by 89 (sum of weights) is 89.89 divided by 11 is 8 with remainder 1/11. Thus 1 is the check digit.