I spent several hours on the calculation part of this problem, trying to find a solution. Our textbook, in my opinion, was not much help. I resorted to 3 other books that I have on JavaScript, plus my internet research. What I discovered is  that the Split Function/Method was the key to breaking the string of values in the textboxes down into an array, which  would be assigned to a variable. The variable could in turn be evaluated in a calculation and assigned to another variable which could be passed back to the text box for display.