Ora si che è chiaro.....
Dim tmpResult As String = ""
Dim partA As String() = Me.TextBox5.Text.Split(vbCrLf)
Dim partB As String() = Me.TextBox3.Text.Split(vbCrLf)
Dim i, c As Integer
Dim numA, numB As Double
For i = 0 To partA.Length - 1
numA = 0
Double.TryParse(partA(i).Replace("*", ""), numA)
For c = 0 To partB.Length - 1
numB = 0
Double.TryParse(partB(c).Replace("*", ""), numB)
tmpResult = tmpResult & Convert.ToDouble(numA * numB).ToString() & vbCrLf
Next
Next
Me.TextBox4.Text = tmpResult
Cristian Barca