FLY的狐狸

【例一】求，即求1!+2!+3!+4!+…+20!。

程序源码：

Option Explicit
Private Sub Form_Click()
   Dim N As Integer, I As Integer, Sum As Double, ChengJi As Double
   Sum = 0
   For N = 1 To 20
      ChengJi = 1
      For I = 1 To N    ' 求I的阶乘
         ChengJi = ChengJi * I
      Next I
      Sum = Sum + ChengJi
   Next N
   Print Sum
End Sub

【例】求Sn=a+aa+aaa+…+的值，其中a是一个数字，例如：2+22+222+2222（此时n=4），n和a由输入框输入。

程序源码：

Option Explicit
Private Sub Form_Click()
   Dim N As Integer, A As String, AStr As String
   Dim I As Integer, J As Integer, Sum As Long
   Sum = 0
   N = Val(InputBox("请输入N的值：", "N:", ""))
   A = InputBox("请输入A的值：", "A:", "")
   For I = 1 To N
      AStr = ""
      For J = 1 To I    ' 此循环用于组合第I项的数字字符串
         AStr = AStr & A
      Next J
      Sum = Sum + Val(AStr)
   Next I
   Print Sum
End Sub