IUPAC name of the compound CH3−CH2−C|CH3|CH3             −CH|             CH2−CH3−CH2−CH3 is

Lowest sum rule is used whenever there are more than one substituents present on the carbon chain. It means numbering is done is such a way that the branched  carbon atoms get the lowest possible number.Right to left 3+4+4=11 (wrong)Left to right 3+3+4=10 (correct)Ethyl comes first rather than methyl while naming not numbering.i.e, 4-ethyl-3,3-dimethylhexane