Jomo
I am not upset. Yes, I agree. We should treat the percent sign as a unit. That is the correct formalism. I agree. (There, I have now said it three times.) After Harry clarified what was being said, I guess I should have said "Mea maxima culpa."
Had I understood what you were objecting to in your very first post, namely the misuse of units, this whole thread could have been truncated long ago. Of course, for a student who seemed not to understand the arithmetic of computing a percentage, a discussion of the proper use of unit symbols may have been wasted. For that student, what you put into a calculator is
[MATH]\dfrac{8}{240} * 100 \approx 3.33.[/MATH] Then write % after the 3.33.
It is that simple operationally. I was giving a procedure, not really an equation.
By the definition of percent, short for per centum meaning in proportion to 100, and by the meaning of the symbol %,
[MATH]\dfrac{8}{240} * 100 \approx 3.33 \implies \dfrac{8}{240} * \dfrac{100}{100} \approx \dfrac{3.33}{100} \implies \dfrac{8}{240} \approx 3.33\%.[/MATH]
That is a logical justification for what we actually do operationally. I am not sure, however, that such an explanation or this thread has helped this student.