Can anyone tell me, since I'm a VBA-virgin, if this routine can be
performed (and how) using just a regular Excel spreadsheet? Thanks so
much!

Sub titanus()
Dim interest(50)
Period = 0
valu = 0

For i = 1 To 50
interest(i) = 5
Next

For Count = 1 To 50
valu = valu + interest(Count)
If valu 100 And Period = 0 Then
Period = Count
End If
Next
End Sub