What it is Module11 well, module11 it is a mathematical algorithm for check errors in a sequence of numbers. Do you wanna know more? please visit this links
The algorithm consist in four steps
- Multiply digits with the sequence
- Sum all results
- Calculate module 11
- Subtract 11 to result
Sequence -> [ 2 , 3 , 4 , 5 , 6 , 7 ]
| Number test | 1 | 5 | 6 | 4 | 6 | 8 | 6 | 1 |
| Sequence | 3 | 2 | 7 | 6 | 5 | 4 | 3 | 2 |
| RESULT | 3 | 10 | 42 | 24 | 30 | 32 | 18 | 2 |
If the length of the test sequence is less than the sequence, just repeat the sequence, in this case we repeat 2 and 3.
3 + 10 + 42 + 24 + 30 + 32 + 18 + 2 = 161
161 mod 11 = 7
11 - 7 = 4
That means the control digit is 4.
If we change a number of the test sequenece 15646861 the control digit will change
The application of this algorithm is varied, from barcode to identification cards of Chile where sometimes we will see a K or a 0 instead of the digit 10 and 11.