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

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 1^st, 3^rd, 5^th and 7^th digits are multiplied by 1
2. The 2^nd, 4^th, 6^th 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

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