Private Sub btnCalculate_Click(sender As Object, e As EventArgs) Handles btnCalculate.Click Dim height As Double Dim width As Double Dim depth As Double Dim capacity As Double height = txt_height.Text width = txt_width.Text depth = txt_depth.Text capacity = (height * width * depth) / 100 ListBox1.Items.Clear() ListBox1.Items.Add("The capacity of the water tank is " & capacity & " Liters") End Sub