Đổi đơn vị đo

3cm2=...............mm2
5dm2=............cm2
4dm2=.............mm2
5m2=..............mm2 
b) 300mm2=...........cm2
500cm2 =............dm2
40000mm2=............dm2
6000000mm2=..............m2
c) 1dm2  23cm2 =.............cm2
30m2 5dm2=.............dm2
20hm2  06dam2=...............