TextBox4.Text = TextBox1.Text * 0.15 + TextBox2.Text * 0.5 + TextBox3.Text * 0.3

4 Textboxes and 1 Button was all the program.

Can anyone tell me how to Calculate Double numbers ? when i type 5.6 6.7 8.4 the program is not calculating right.. is working only with integer numbers :/