Another method of calculating a check digit

The eight digit ID number being used in this example is broken down as follows:

 XXXXXXX X 7 digits unique identification 1 digit self check digit

The first seven digits are all that are required to identify a record on the file. The eighth digit is included to reduce the possibility of entering the wrong identification/account number.

The self check digit: The self check digit is calculated from the first seven digits as follows:

1. The 1st, 3rd, 5th and 7th digits are multiplied by 1
2. The 2nd, 4th, 6th digits are multiplied by 2
3. The resulting digits are added (this means if the answer from the multiplication is a 2 digit number, both digits are added)
4. The sum is subtracted from 100
5. The last digit of the difference becomes the check digit

EXAMPLES:

The seven digit identification/account number is: 4175036

• 4, 7, 0, 6 are multiplied by 1

• 1, 5, 3 are multiplied by 2

 4 1 7 5 0 3 6 x1 x2 x1 x2 x1 x2 x1 4 2 7 10 1 6 6

• The results are added: 4 + 2 + 7 + 1 + 0 + 6 + 6 = 26 (note: added 1 and 0)
• The sum is subtracted from 100: 100-26=74
• The last digit of the difference, in this case 4, is the check digit

The identification/account number is 41750364

The seven digit identification/account number is: 4711924

• 4, 1, 9, 4 are multiplied by 1
• 7, 1, 2 are multiplied by 2

 4 7 1 1 9 2 4 x1 x2 x1 x2 x1 x2 x1 4 14 1 2 9 4 4

• The results are added: 4 + 1 + 4 +1 + 2 + 9 + 4 + 4 = 29
• The sum is subtracted from 100: 100-29 = 71
• The last digit of the difference, in this case 1, is the check digit

The identification/account number is : 47119241