Ответ:

1) 2345 = 2000 + 300 + 40 + 5 = MM + CCC + XL + V = MMCCCXLV.

2) 1987 = 1000 + 900 + 80 + 7 = M + CM + LXXX + VII = MCMLXXXVII.

3) MMCCXL = 2000 + 200 + 40 = 2240.

4) DCLXX = 500 + 100 + 50 + 20 = 670.