输入正整数1～n中所有能被3和7整除的数字,数字的和,数字的个数.

这个很简单的...
给你个样本：
Private Sub Command1_Click()
On Error Resume Next
Dim i As Long,s As String
Dim n As Long,sum As Long
s = InputBox("输入正整数n","输入",100)
If s = "" Then Exit Sub
n = Val(s)
If n