The prefix #"deci"-=10^-1#. The prefix #"centi"-=10^-2#. The prefix #"milli"-==10^-3#. And going the other way, the prefix #"kilo"-=10^3#, and the prefix #"mega"-=10^6#.
And so #1*dm-=1xx10^-1xx1000*mm-=100*mm-=10*cm#.
We use #1*dm^3-=(10^-1*m)^3-=1/1000*m^3-=1*L# as a convenient measurement of volume.