here is how u do that..
its tried and tested and it works fine ..


Dim strMyNumber As String
Dim n As Long
Dim myNumber As Double
Dim inArrays(10) As String, CouNts As Integer
CouNts = 0


myNumber = InputBox("Plese inter a number", "Put dot after 3 numbers")
Dim nums As String

strMyNumber = CStr(myNumber)
inArrays(CouNts) = Mid(strMyNumber, 1, 3)& "."

For n = 4 To Len(strMyNumber) Step 3
CouNts = CouNts + 1
inArrays(CouNts) = Mid(strMyNumber, n, 3) & "."
Next n

For n = 0 To CouNts
nums = nums & inArrays(n)
Next n

nums = Left(nums, (Len(nums) - 1))

MsgBox "here is your number: " & nums, , "Get numbers"