Roman numerals

This year we are learning about Rome.We learned about roman numerals.

1=l
2=ll
3=lll
4=lV
5=V
6=Vl
7=Vll
8=Vlll
9=lX
10=X                                                                                                                                                        
50=L
100=C
500=D
1,000=M

There is no zero in roman numerals!So it is very hard to do math.