Subs? Or another way to "remove" symbolic variable from equation

Hello, good day to all of you.

I've got a problem. I've got » many « equations in my calculations with results (only numbers) which I need. All of the equations are dependent on the --first-- equation.

For example, my 15th equation will result in number result=700.

And in the end I need it to my

 disp(['Text' num2str(result) 'N'])

But I -have to- add symbolit variable (F_dop) in my first equation. So the others will be functions of this variable.

In my 10th equation I have to do some partial derivative diff(function,F_dop) and use the result.

 Then I say that F_dop = 0.

I expected that the 11th through 20th equations will be just numbers, because the F_dop = 0 so it doesn't have any effect on the calculation and I expeted that the 15th equation will be still result=700.

BUT

It's result=700+Fdop (for example...). So it's still! function of the symbolic F_dop.

So now, as I calculate almost averything, I have to write result = subs(result) to get the result = 700 number only that I'm able to put in the disp(['']) function.

Is there any way to say F_dop = 0 and make to program to compute with normal single / double and NOT symbolic?