Private Sub Command1_Click()
Dim n As Integer
s = 0
n = InputBox("N=")
y = 1
For i = 2 To n + n Step 2
y = y * (i - 1) * i
If i Mod 4 = 2 Then s = s + 1 / y Else s = s - 1 / y
Next i
Print "n="; n
Print "sum="; s
End Sub
Private Sub C1_Click()
Dim i As Integer, sum As Single
Dim n As Integer, t As Integer
n = Val(InputBox("", , 10))
t=1
For i = 1 To n
sum = sum + 1 / (2 * i) * t
t = -t
Next
Print sum
End Sub