help with finding zeros for 100!

[ludask]

hi all
using VB2005
im trying to write a code to find number of zeros of 100! but cant get it to work properly?
help would be good
heres the code ive done so far

Public Class Form1

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
Dim i As Integer = 0
Dim num As Integer = 0
Dim start As Integer = 0
Dim theend As Integer = 100


While (start <= 100)

num = start
While (start Mod 5 = 0)
start = start / 5
i += 1

End While
start = num

While (start Mod 2 = 0)

start = start / 2
start += 1

End While

End While

Label1.Text = i





End Sub
End Class

[redhead]

Think about the values here

While (start <= 100)
  num = start  # num and start equals 0
  While (start Mod 5 = 0)  # 0 mod 5 is 5, this is never entered
    start = start / 5  # 0/5 is 0 start is still 0
    i += 1 # i is incremented 1, but since we never entered, it will never be incremented
  End While
  start = num # since num is the orriginal start value, start is still 0
  While (start Mod 2 = 0)  # 0 mod 2 is 2, this is never entered
    start = start / 2 # 0/2 is 0, start will never change
    start += 1 # start is incremented, but since we never entered start never gets incremented
  End While
End While