Adding $ prefixes and subfixes of .00 while not affecting dynamic variable

I can add them to the set variables in a literal string such as

var hourlyChaser = “$” + 10 + “.00”;
hourlyPartsChaser.text = hourlyChaser;

but that affects the variable when I want to call it into a dynamic and gives me a NaN

is there way to add and subtract these strings to it will not affect the actual input when I need to call it to add it another number variable?