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    Hi everyone,
    So I know a major constituent of the naming process is that lowest sum of carbon position of any additional groups should be used. However, my teacher also told me Methyl groups should be assigned numbers first, thus giving methyl the lowest possible positional values.
    Which rule should be obeyed when, for example, giving methyl the lowest possible coefficient, so to speak, would increase the sum of the numbers? If that makes sense....

    It's actually not true that the lowest sum of carbon position (or locants) should be used. That is a misconception. I'm going to copy and past from the wikipedia article on IUPAC nomenclature of organic chemistry (which is really a good read for chemistry students). Organic chemical compunds should be numbered so that it

    1. Has the lowest-numbered locant (or locants) for the suffix functional group. Locants are the numbers on the carbons to which the substituent is directly attached.
    2. Has the lowest-numbered locants for multiple bonds (The locant of a multiple bond is the number of the adjacent carbon with a lower number).
    3. Has the lowest-numbered locants for prefixes.
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