I've used somewhere between 66 and 100 programming languages in my career, depending on how you count. In my early career I would often learn the language on the job, it doesn't take me long to become expert. A lot of those languages were "We got this ancient system written in an obscure language no one has ever heard of, point onefang at it, he'll sort it out". My party trick amongst geeks is to learn a programming language in an hour. Did that for an exam once, with the blessing of the IT department head, first cracked the textbook open an hour before the exam started, got top marks.