1. a poate fi 1,2,3,4,5,6,7,8,9
b poate fi 2,4,6,8,0
2. 101,202,303,404,505,606,707,808,909, deacuma in loc de 0 punem 1
,212,313,414,515......
313,323,343.......
414,424,434,454......
si continui pana la 919,929,939.......989 ( este ultimul)
3. 1234, 1432, 2134, 2314, 3124, 3142, 4312, 4132