2. DL, MDX, MMXVI
13. 1900, 59, 18021
14. a) 254450
b) 254500
c) 254000
d) 250000
e) 300000
15. 333333, 233333, 133333, 33333.
16. 202020, 242424, 262626, 404040, 424242, 464646, 606060, 626262, 646464, 686868, 282828, 484848, 808080, 828282, 848484, 868686.