For Möbius systems there is an odd number of plus-minus sign inversions in the basis set in proceeding around the cycle. A circle mnemonic was advanced which provides the MO energies of the system; this was the counterpart of the Frost–Musulin mnemonic for ordinary Hückel systems. It was concluded that 4n electrons is the preferred number for Möbius moieties in contrast to the common 4n + 2 electrons for Hückel systems.