Программа для рассчёта по формуле

Public Class Form1
    Private Sub nachalo() Handles Me.Load
        TextBox1.Text = 7
        TextBox2.Text = 5
        TextBox3.Text = 8
        TextBox4.Text = 2.5
        TextBox5.Text = 2.6
        TextBox6.Text = 2.7
        TextBox7.Text = 4
    End Sub
 
    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        Dim s As Single, k As Single, R As Single, m As Integer
        Dim n1 As Single, n2 As Single, n3 As Single
        Dim z1 As Single, z2 As Single, z3 As Single 'промежуточные значения
        s = CSng(TextBox1.Text) : k = CSng(TextBox2.Text) : R = CSng(TextBox3.Text) : m = CSng(TextBox7.Text)
        n1 = CSng(TextBox4.Text) : n2 = CSng(TextBox5.Text) : n3 = CSng(TextBox6.Text)
        If n1 = 0 Or n2 = 0 Or n3 = 0 Or m = 0 Then
            MsgBox("Значения n1, n2, n3, m не равны нулю")
        Else
            z1 = ((s * m) / n1) : z2 = ((k * m) / n2) : z3 = ((R * m) / n3)
            Label7.Text = "Ответ = " + CStr(z1 + z2 + z3)
        End If
    End Sub
End Class