[2] Percent of freelancers working in the following fields:

Freelance category


% of total

Technical editing



Technical writing



Information design






Although "working" could well be changed to "who work", it's not wrong. The real errors lie in the table. If you check the percentages carefully, you'll see that the first two numbers have been correctly rounded upwards, from 7.5 and 87.5%, respectively. One common rule for rounding numbers is to round up halves to the next-highest number. (A variant of that rule suggests that you should round upwards only if the result is an even number, and round down otherwise.) By the way, did you notice that "percent" should be "percentage"?

Unfortunately, the result of rounding is that the percentages add up to 101%, which is clearly wrong. Though some readers will never notice and others will understand the source of the problem, others will spot the error and decide that your mathematical skills are suspect. There are two easy solutions: First, present all percentages with enough decimal places that you don't have to round any numbers. Second, add a footnote stating that "percentages don't add up to 100% because of rounding".

A good editor will perform this and other reality checks on your numerical data to ensure that you aren't sending any mixed messages about your mathematical skills.