上面那个程序就是如何把它在窗体上输出，试了一下，但是说参数不对

Option Explicit
Function IsPrime(ByVal n As Long) As Boolean
Dim i As Long
For i = 2 To Int(n / 2)
If n Mod i = 0 Then IsPrime = False: Exit Function
Next
IsPrime = True
End Function

Private Sub Form_Load()
Show
Dim i As Long
Dim a As String
For i = 1 To 100
a = IsPrime(i)
If a = True Then Print i
Next i
End Sub

等下

Private Sub Command1_Click()
Dim i As Long, sum As Variant
For i = 2 To 10000000
If prime(i) Then Print sum '在窗体输出
Next i
End Sub
Private Function prime(n As Long) As Boolean
Dim j As Long
For j = 2 To Sqr(n)
If n Mod j = 0 Then Exit Function
Next j
prime = True
End Function

筛素数:筛法求2～1000之间的所有素数
http://www.crazycoder.cn/CDevelopment/Article14351.html