And the likes of log(2) also. I had in mind things that are literally numbers (to @EVAL) ... like the various built-in functions.There's @ISFLOAT. But if a string is not a number, @EVAL may interpret it as the name of an environment variable. Which may or may not be defined, which might or might not be a valid number. And then there are other strings like AND and SHR, which are not numbers, and PI, which is.... This is not a trivial question!