Calculation of Surface Area and Volume of Sphere

Public Class Form1
    Dim rad, sa, vol As Single
    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
     

    End Sub

    Private Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
        Const PI As Single = 3.142
        rad = TextBox1.Text
        sa = 4 * PI * rad * rad
        vol = (4 * PI * rad * rad * rad) / 3
        TextBox2.Text = sa
        TextBox3.Text = vol
    End Sub
End Class