I'm a resident of Kuwait and I just learnt that the CIVIL ID numbers allotted to us follow a checksum. The ID is 12 digit number following the algorithm below -
11 – Mod(( c1 * 2 ) + ( c2 * 1 ) + ( c3 * 6 ) + ( c4 * 3 ) + ( c5 * 7 ) + ( c6 * 9 ) + ( c7 * 10 ) + ( c8 * 5 ) + ( c9 * 8 ) + ( c10 * 4 ) + ( c11 * 2 )),11) = The 12th Digit
Here, Cx are the digits in the Civil ID number.
Can someone tell me what is the reasoning behind the coefficients used in the checksum? The Bulgarian civil number also uses a checksum but the algorithm used there uses powers of 2 modulus 11. More info here.