To add two numbers [Ajouter deux nombres].

                    
                                additive identity
                                        |
                                       \|/
                                        '                             *
                                        0         1         2         3         4         5
                                        |=========|=========|=========|=========|=========|...
                    |=========|=========|=========|=========|=========|...
                    0         1         2         3         4         5
                                        *                             '
                                                                     /|\
                                                                      |
 
                                                                  2 + 3 = 5

How to multiply two numbers with two rules?