A triple for-loop from our exam...

First of all, please move this thread if it is in totally wrong place.

Anyway, I took today in our university an exam in Discrete Mathematics. The question itself was easy and I know the answer too (by counting it with computer), but what is the formula to solve this? Here's the code as VBA code:

Code:

`Sub forlooptask()`

Dim i As Long, j As Long, k As Long, x As Long

For i = 1 To 200

For j = 1 To i - 1

For k = 1 To j

x = x + 1

Next k

Next j

Next i

Debug.Print x

End Sub

the result is 1333300. The question is: **How does the equation for solving this go? Where does that 200 go to?**