What Is the Checksum of an ORCID Number?

The Checksum of an ORCID Number is the last digit of the ORCID number.

For example, Stephen Hawking's ORCID is "0000-0002-9079-593X". The last digit X is the checksum, which is calculated using the "MOD 11-2" algorithm.

Here is the "MOD 11-2" algorithm to carry out the checksum calculation:

1. Initialize a sum value to 0.

2. Loop through each of the first 15 digits of the ORCID code from left to right.

2.1. Add the current digit to the previous sum, then multiply by 2.

3. Take the remainder from the final sum modulo 11.

4. Subtract the remainder from 12.

5. Take the remainder as the checksum from subtraction result modulo 11.

6. If the checksum is 10, convert it to letter X.

Using "0000-0002-9079-593X" as an example, the "MOD 11-2" algorithm can be illustrated below:

sum = 0 
sum = (0 +    0) * 2 = 0
sum = (0 +    0) * 2 = 0
sum = (0 +    0) * 2 = 0
sum = (0 +    0) * 2 = 0
sum = (0 +    0) * 2 = 0
sum = (0 +    0) * 2 = 0
sum = (0 +    0) * 2 = 0
sum = (2 +    0) * 2 = 4
sum = (9 +    4) * 2 = 26
sum = (0 +   26) * 2 = 52
sum = (7 +   52) * 2 = 118
sum = (9 +  118) * 2 = 254
sum = (5 +  254) * 2 = 518
sum = (9 +  518) * 2 = 1054
sum = (3 + 1054) * 2 = 2114
remainder = 2114 % 11 = 2   
checksum = (12 - 2) % 11 = 10 
checksum = X

⇒ URN for ORCID Number

⇐ What Is ORCID (Open Researcher and Contributor ID)

⇑ Introduction of ORCID

⇑⇑ ORCID (Open Researcher and Contributor ID)