pls.help dau p si coroana

Răspuns:
a)52, 235, 253, 352, 523, 532
b)1234, 2132, 3124, 3214, 3412, 4213
c)33, 303, 330, 3333, 30003, 33003, 333333
d)135, 351, 135135, 153153, 351351, 513513