1.π=2*22/(1*3) *42/(3*5) *62/(5*7) *… ...
2.π/4＝(1-1/3+1/5-1/7+1/9-…）
3.(π^2)/6=1/(1^2)+1/(2^2)+1/(3^2)……
Private Sub Command1_Click()
Dim i As Long, pi As Double, k As Integer, m As Double
i = 1
k = 1
pi = 0
m = 1
While (m > 0.00001) '設定精度
m = 1 / (2 * i - 1)
pi = pi + k * m
i = i + 1
k = -k
Wend
Print "π/4近似值 "; 4 * pi
End Sub