# IUPAC numbering of carbon atoms in a chain

A chemistry handout for nomenclature of org. compounds I've been reading states a particular rule for every functional group viz.

If there is a choice in numbering not previously covered, the parent chain is numbered to give the substituents the lowest number at the first point of difference.

Can anyone explain what it means?

$\ce{CH3-CH2-CH2-CHCl-CH2-CH3}$