Identification numbers with check digit algorithms 
Instructions
1. Move green dots with mouse to "write" the Identity Card number (BI). For example, for the numbe \(11866607\), you need to place dots as follows:
2. The first orange dot shows the check number in case the system would be well designed, while the second one shows the check digit that appears in the Portuguese Identity Card. In the example above, they are \(X\) and \(0\), respectively.
