molecule, C₁₄H₁₀, has three rings so that the rule gives the number of sigma bonds as 24 + 3 - 1 = 26. In this case there are 16 C-C sigma bonds and 10 C-H bonds.

This rule fails in the case of molecules which, when drawn flat on paper, have a different number of rings than the molecule actually has - for example, Buckminsterfullerene, C₆₀, which has 32 rings, 60 atoms, and 90 sigma bonds, one for each pair of bonded atoms; however, 60 + 32 - 1 = 91, not 90.