Spiranes
Spiro[4.5]decane
Order: The smallest cycle first
Bicycloalcanes
Bicyclo[3.2.0]heptane
Order: The biggest cycle first
Numerotation
Spiro[4.5]decane
Start with the first C of the smallest cycle
Bicyclo[3.2.1]octane
Start with a C of the bridge, then number the branches in descending order of their length
Examples
6-Methylspiro[4.5]decan-1-ol
Bicyclo[3.1.1]hept-2-ene