visual basic：通过单击事件动态添加的文本框如何引用其中输入的内容进行运算？

添加文本框：

Private Sub plus_Click()
Dim qianglei, zuofa, zuofa_s, cailiao, cailiao_s, jisuan As Object
Static a1, a2, b1, b2, c1, c2, x1, x2, y1, y2, z1, z2, N As Long
N = N + 1
Set qianglei = Form1.Controls.Add("VB.textbox", "qianglei" & a1)
    With qianglei
    .Visible = True
    .Width = 1455
    .Height = 315
    a2 = a2 + 500
    .Top = a2
    .Left = 360
    a1 = a1 + 1
    End With
Set zuofa = Form1.Controls.Add("VB.textbox", "zuofa" & b1)
    With zuofa
    .Visible = True
    .Width = 700
    .Height = 315
    b2 = b2 + 500
    .Top = b2
    .Left = 1920
    b1 = b1 + 1
    End With
Set zuofa_s = Form1.Controls.Add("VB.textbox", "zuofa_s" & x1)
    With zuofa_s
    .Visible = True
    .Width = 700
    .Height = 315
    x2 = x2 + 500
    .Top = x2
    .Left = 2650
    x1 = x1 + 1
    End With
Set cailiao = Form1.Controls.Add("VB.textbox", "cailiao" & c1)
    With cailiao
    .Visible = True
    .Width = 700
    .Height = 315
    c2 = c2 + 500
    .Top = c2
    .Left = 3480
    c1 = c1 + 1
    End With
Set cailiao_s = Form1.Controls.Add("VB.textbox", "cailiao_s" & y1)
    With cailiao_s
    .Visible = True
    .Width = 700
    .Height = 315
    y2 = y2 + 500
    .Top = y2
    .Left = 4230
    y1 = y1 + 1
    End With
Set jisuan = Form1.Controls.Add("VB.commandbutton", "jisuanbutton" & z1)
    With jisuan
    .Visible = True
    .Width = 300
    .Height = 280
    z2 = z2 + 500
    .Top = z2
    .Left = 5100
    z1 = z1 + 1
    End With
Dim jieguo As Object
Static p1, p2 As Long
Set jieguo = Form1.Controls.Add("VB.label", "jieguo" & p1)
    With jieguo
    .Visible = True
    .Width = 1455
    .Height = 315
    p2 = p2 + 500
    .Top = p2
    .Left = 5600
    p1 = p1 + 1
    End With
jieguo = zuofa_shuju * qianglei_shuju
End Sub

我想通过这个单击事件添加几个文本框和一个按钮，然后单击按钮后选取其中文本框的内容进行运算并输出结果。
求指教

Dim s As String = CType(Form1.Controls("qiwen"), TextBox).Text
...