Luhn is also used for the last digit in Swedish social security numbers, https://en.wikipedia.org/wiki/Personal_identity_number_%28Sweden%29#Checksum https://en

Luhn is also used for the last digit in Swedish social security numbers, https://en.wikipedia.org/wiki/Personal_identity_number_%28Sweden%29#Checksum https://en.wikipedia.org/wiki/Personal_identity_number_%28Sw... which makes me remember doing this in school around age of 10. i wish the teacher then would call it an "algorithm", so one wouldnt grow up thinking "algorithms" is something complex and hard to understand