Option Explicit


Sub pi()

Dim eps As Double
Dim res As Double
Dim pi As Double
Dim pre As Double
Dim i As Integer

i = 0
pi = 4

eps = [C3]

Do
    pre = pi
    res = (-1) ^ i
    res = res * 4
    res = res / (2 * i + 1)
    pi = pi + res
    i = i + 1
Loop While Abs(pi - pre) > eps

[C4] = res

End Sub