Radio button. How do I give a numeric value to it?

Question

Hi,
This is my first time working on Windows form, and I need some help.

I have 2 radio buttons, and I want to know how to give numeric values to them in order to use them in future formulas
(ex: if selected yes, it will be -100 from total. If selected no, it will be +5 from total)

o Yes             o No

so far, I only got to this on MainForm.cs:

yesButton.Checked = true;
noButton.Checked = true;

Which, I am not even sure if I am on right track...

Help!  D: