On the TvTropes page "Everybody Hates Mathematics", in the section of examples from "Real Life", there appears the following excerpt:
Isaac Asimov once wrote in an editorial that the reason so many women are becoming lawyers — as opposed to doctors, engineers and so on — is that it is the only high-powered profession that requires no mathematics. He was promptly flooded with letters from irate lawyers claiming that they do, too, have to do math: they have to calculate billable hours, and figure taxes, and .... Asimov replied, in effect, "I rest my case". It is very common for people in all walks of life to equate mathematics with arithmetic.
The obvious searches didn't turn up anything, so I'm left wondering if this is made up, or maybe a wrong recollection by an editor of the page.