Thank you so so much for this. I haven't had a chance to put it to the test yet, but this definitely is getting my mind a step in the right direction!

I apologize for not making the first equation clear, upon second glance I see how it is confusing. Here is what I am trying to say:

a - b = c

c * 2 = sum (d)

d / 0.9 = sum

Basically I am subtracting two numbers to get that sum, then taking that and multiplying by 2, and then finally taking the sum of that and dividing that by 0.9 to get to the final answer.

I am using QtCreator 5.5. I have 4 default source files that are associated with a new project (mainwindow.h, main.cpp, mainwindow.cpp, and mainwindow.ui). Where would this Qt code going that you are giving? In the mainwindow.cpp?

I prefer the batch method of generating answers. I have a button in the UI that I am trying to connect that when I press the "calculate" button, it runs the calculations and generates data.

As far as the range calculations, the inputs wouldn't be in between 0.19 and 0.20. The numbers that we input will only be in the tenths but you hit the nail on the head with the inequality calculations. But in this case I failed to mention that I am inserting the input number into a LineEdit and the output number is going to a LineEdit too. I don't feel as though QDoubleValidator will be necessary for any number over 1.10 is 25 so that basically covers all numerical ranges. I do appreciate that wisdom though because I was not aware of that option, same as the trigger based calculations that you had given above, I am sure they will be useful to me. Thank you so much for all of your help so far and I hope that my reply has explained some of the misconceptions. I appreciate all of your time and effort.