Check Digit
The NHI Number contains a check digit. The algorithm for generating the digit is described below:
Each alpha character is given a numeric representation equivalent to its ordinal position within the alphabet, starting at A through to Z. The letters I and O are omitted making the ordinal range 1 - 24.
Each alpha character's numeric representation is multiplied by the inverse of its ordinal position within the NHI Number. The first value is multiplied by 7, the second by 6 and so on.
The first 3 numeric characters are multiplied by the inverse of their ordinal position also.
The sum of these multiplications modulus 11 subtracted from 11 is taken as the check digit (a result of 10 is translated to 0).
This scheme is similar to the ISBN 10 check digit scheme.
Read more about this topic: NHI Number
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