Private Sub Command1_Click()
a = Val(Text1)
b = Val(Text2)
For i = a To b
If prime(i) Then Text3 = Text3 & i & vbCrLf
Next i
End Sub
Private Sub Form_Load()
Text1 = ""
Text2 = ""
Text3 = ""
End Sub
Function prime(n) As Boolean
prime = False
For i = 2 To Sqr(n)
If n Mod i = 0 Then Exit Function
Next i
prime = n > 1
End Function