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.