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:

- The 1
^{st}, 3^{rd}, 5^{th}and 7^{th}digits are multiplied by 1 - The 2
^{nd}, 4^{th}, 6^{th}digits are multiplied by 2 - The resulting digits are added (this means if the answer from the multiplication is a 2 digit number, both digits are added)
- The sum is subtracted from 100
- 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**