To determine the conversion from mm to cm to m to dm to km:
![\begin{gathered} \operatorname{mm}\text{ => Millimtere} \\ \operatorname{cm}=>\text{centimetre} \\ m\Rightarrow\text{ metre} \\ dm\Rightarrow\text{ decimetre} \\ \operatorname{km}-\text{kilometre} \end{gathered}]()
Conversion from mm to cm =

Conversion from cm to m
![100\operatorname{cm}\Rightarrow\text{ 1m}]()
Conversion from m to dm

Conversion from dm to km

Hence the correct conversion are
10 mm = 1 cm
100 mm = 1 dm
1000 mm = 1 mm
1000000 mm = 1 km