As a general rule that's probably fine, but in cases where a variable is confusing either a better name or a explanatory comment is probably appropriate. Ideally you'd pick a name that fully captures the intent of the variable, but in this case it's rather vague, and a name that isn't would be rather unwieldy, so a comment is a nice compromise. The alternative would be to call it something like:

    unsigned current_power_of_three = 1;

or something equally verbose. I'd expect such silliness in some enterprisey java code, but I think most people would agree a short explanatory comment is probably the superior choice.