Final answer:
Numerical prefixes like di-, tri-, and tetra- are used to denote multiple identical branches in the chemical naming of organic compounds, and alphabetization is based on the branch's stem names, not the prefixes.
Step-by-step explanation:
When naming organic compounds that have multiple branches of the same type, numerical prefixes are used. If there is more than one identical substituent group attached to the carbon chain, the names of such groups will be prefixed with di-, tri-, tetra-, and so on, to indicate the number of identical groups. These prefixes are placed before the branch name in the overall compound name. Additionally, while alphabetizing substituent names, these prefixes are not taken into account, and the alphabetization is based on the stem of the branch name itself. For example, 'dimethyl' would be alphabetized as if it were 'methyl.'