By the way, if your results are returning a value of NaN, you need to remove things like commas from the equation. Commas in ActionScript are used for things like declaring a series of variables or creating an array, so when you type in a comma, it doesn't register as a string but rather you're telling the interpreter that a value like, say, "2,509" for your B/P score is actually two separate values; 2 and 509.
Scottmale24 didn't anticipate this and didn't optimize his code to accept commas as a string, only as raw script input, which means commas are taken as code by the interpreter. Had he programmed it to take string data rather than raw numbers, that would allow him to convert the string back into a numeric value while removing string values like letters and punctuation marks so the raw number data could be plugged back into the calculator without error.
When an SWF file returns a value of NaN, you've probably entered a value that the interpreter doesn't understand or you've accidentally entered in actual ActionScript code that undermines the program's design. You can actually cause Flash to redefine variable datatypes by giving it inappropriate values like letters, which will cause Flash to redefine a mathematical variable to a string. This is because Flash is capable of accepting what's called "implicit programming", where if a variable is left undefined in datatype and you plug in a value, the interpreter will attempt to fill in the blanks and assign a datatype for you.