a) 48 = 2 * 2 * 2 * 2 * 3
144 = 2 * 2 * 2 * 2 * 3 * 3
2 * 3 = 6 si 48
b) 231 = 3 * 7 * 11
693 = 3 * 3 * 7 * 11
3 * 7 * 11 = 231 si 231
c) 1890 = 2 * 3 * 3 * 3 * 5 * 7
2268 = 2 * 2 * 3 * 3 * 3 * 3 * 7
2 * 3 * 7 = 42 si 378
d) 372 = 2 * 2 * 3 * 31
360 = 2 * 2 * 2 * 3 * 3 * 5
900 = 2 * 2 * 3 * 3 * 5 * 5
6 si 12