Overflow

Am creating a store managemaent system using Access 2003. On doing multiplication when the answer is more than 2 billions am getting message "Run-time error 6" Overflow.
Here is the codes


Private Sub txtvalue_Click()
Dim num As Long, x As Long, y As Long

x = CLng(txtuvalue)
y = CLng(txtquantity)

Me.txtvalue= x * y
End Sub

Does it mean Access 2003 can perform multiplication to an answer of 2 billion only??
Thanks for your consideration.