## percent symbol usage in writing

Ok, I've been searching all moring and haven't had a clear defining answer yet. I would like to know how to use the % symbol properly in my technical writing.

ie. The motor speed is set in the range of 0 to 100%.

Is there to be a percent sign after the 0 as well? Do I just spell out the word percent at the end? HELP!!

I think in that instance you might be better off using: 0 to 100 percent.

That's what I was leaning towards, but wanted another opinion. Thanks! Greatly appreciated.

You could use 0 percent to 100 percent (with the symbols), but that would sound stuffy.

You could also go with 0-100% (with an en dash where I used a hyphen).

The Chicago Manual of Style, 15th Ed. gives the following guideline:

9.19 Percentages. Percentages are always given in numerals. In humanistic copy the word percent is used; in scientific and statistical copy, or in humanistic copy that includes numerous percentage figures, the symbol % is more appropriate.

Only 45 percent of the electorate voted.
With 90–95 percent of the work complete, we can relax.
A 75 percent likelihood of winning is worth the effort.
Her five-year certificate of deposit carries an interest rate of 5.9 percent.
Only 20% of the ants were observed to react to the stimulus.
The treatment resulted in a 10%–15% reduction in discomfort.