Hexane $\ce{C6H14}$ has 5 isomers, but I'm able to draw at least 6 different structures, which initially led me to think that there were 6 isomers.
So how can I tell which structure will qualify as an isomer?
The only rule my textbook suggests is connectivity exemplified as a $\ce{CH3}$ (for example) that runs downward at the end of the straight chain, which is no different than the straight chain itself.