Lack of congruence in mathematical abilities versus writing abilities in faculty Because of my background in mathematics and statistics, I have been called upon by my department (the Math/Stat Department) to assist faculty members from the humanities and linguistics departments in performing routine statistical analyses for a few of their publications. While the actual statistical analysis is very low level (basic undergraduate statistics), I am of course more than happy to do the simple work and be given co-authorship on a paper. 

However, in the course of performing these statistical tasks, I have found that some of these professors do not even know how to perform elementary tasks such as finding the average of a set of numbers, adding fractions with single digit denominators, or calculating 45 cubed ("There's no button for that on the calculator!"). These are all tasks that I literally knew how to do when I was in elementary school. It did not take a PhD in math to know how to do these things (or even a high school diploma). 

Because of this, I have begun to wonder why we seem to be completely fine with supposedly  "well-educated" (is that too harsh?) people being entirely incompetent at mathematics. Some of these people that I am asked to help have what I would deem to be 2nd or 3rd grade math skills. What if I, as a math researcher, only wrote on a 2nd or 3rd grade level and had to call upon the English department to write my papers for me?  Or what if I could not even identify who painted the Mona Lisa (or that such a painting even existed)? 

Should I suggest that my university begin encouraging 'non-math' faculty to become more competent in core mathematics?

I am not saying that these professors are charlatans and do not deserve their faculty positions. They are very knowledgeable on the specifics of their topic. And I am not trying to berate people for whom math is not their strongest subject. However, I wonder if there are steps that the academic community could begin to implement that would enforce a higher standard of competence in basic mathematics among "non-math" faculty.
Writing is part of your everyday life and an essential job skill, as a STEM academic. The comparison between your writing skills and the basic math skills of a humanities professor is only valid to the extent that these math skills matter for the humanities professor's job. By all means, if their mathematical inability is hindering their research or teaching, they should brush up. But frankly, I trust them to make that call, and to seek out the many resources that are already available for that purpose, if necessary. If they need "encouragement" to do this, I question whether it would be all that helpful. You could teach them to add fractions, but if they didn't use it regularly, they'd forget again. If your only reason for why they should know math is that you as a STEM academic know how to write, I think it's a stretch. It would be like a physical education professor coming to the math department and saying "I remember geometry, why can't all of you lift weights?"