How to bring radio button value to a class.

You can create a class for your logic. Inside that class you can create a static method.

    class Logic
    {
        public static double RadioValue(bool fR1, bool fR2, bool fR3)
        {
            if (fR1) return 1.56;
            if (fR2) return 4.1;
            if (fR3) return 4.2;
            return 0;
        }
    }

The method takes three bools (representing the values of the three radiobuttons).

In the form (example below uses a button to get the double value), you can call the method as shown

    private void button1_Click(object sender, EventArgs e)
    {
        double val = Logic.RadioValue(radioButton1.Checked, radioButton2.Checked, radioButton3.Checked);
        label1.Text = val.ToString();
    }

You can put all your logic methods in the logic class.