The file was never saved and is lost now but I kept a screenshot revealing the bold "secret".
The last line shows how it looks legitimately from a display point of view. You may notice, the on contrary to real Mathacd, the result of prime is WRONG!!!! If we delete the explicit multiplication sign to make an implicit one, Prime gives a wrong result and obviously assumes a pair of parenthesis which is not there! An impicit and an explicit multiplication should give the same result (as its the case in Mathcad).
Unfortunately it seems not to be possible to add a space in a variable or function name (as in your example in MC15).
BTW, the character ÷ can be input via ALT-246 (numeric key pad).
Have you tried to convert your MC15 sheet to Prime? What happens?
