Algoritma Pencari Bilangan Prima

Private Sub Command1_Click()
Dim a, i, j, n, t As Double
Dim x As Double
a = CDbl(Text1.Text)
x = Sqr(a)
n = x
t = 0
For i = 2 To n
If a Mod i = 0 Then
Label1.ForeColor = &HFF&
Label1.Caption = "bukan prima"
t = t + 1
j = i
Label2.Caption = j
i = n
End If
Next
If t = 0 Then
Label1.ForeColor = &HFF0000
Label1.Caption = "prima"
Label4.Caption = i
Label2.Caption = ""
End If
End Sub