Question

VB编程s=1/(1*2)+1/(2*3)+1/(3*4)+....+1/n*(n+1) 要求：N自己确定。

窗体如下

Answer 1

看看这个行吗？Private Sub Command1_Click()
Dim s, n As Double
n = InputBox("请你输入数值：", "提示")
For n = 1 To n
s = s + 1 / (n * (n + 1))
Next n
MsgBox s
End Sub

Answer 2

Option ExplicitPrivate Sub Command1_Click()
Dim sum As Double, i As Integer
For i = 1 To Val(Text1)
sum = sum + 1 / i / (i + 1)
Next
Label1.Caption = sum
End SubPrivate Sub Form_Load()
Label1.Caption = "": Text1 = 10: Command1.Caption = "计算"
End Sub

Answer 3

Private Sub Command1_Click()
Dim n As Double
Dim i As Integer
n = 0
For i = 1 To Int(Val(Text1.Text))
n = n + 1 / (i * (i + 1))
Next i
Label1.Caption = n
End Sub