Is it true that for Huckel’s rule, if you solve for n and obtain a fraction, that it does not work? (No. The rule still works. It means that the system is not aromatic or it is antiaromatic. If you want to challenge the rule, make the system non-planar, or break the continuous conjugation by sp3 atoms, or introduce a bunch of additional cycles (polycyclic system). - GS).